/**
* Copyright (c) 2008-2013, http://www.snakeyaml.org
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.yaml.snakeyaml.scanner;
import java.nio.ByteBuffer;
import java.nio.charset.CharacterCodingException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;
import org.yaml.snakeyaml.error.Mark;
import org.yaml.snakeyaml.error.YAMLException;
import org.yaml.snakeyaml.reader.StreamReader;
import org.yaml.snakeyaml.tokens.AliasToken;
import org.yaml.snakeyaml.tokens.AnchorToken;
import org.yaml.snakeyaml.tokens.BlockEndToken;
import org.yaml.snakeyaml.tokens.BlockEntryToken;
import org.yaml.snakeyaml.tokens.BlockMappingStartToken;
import org.yaml.snakeyaml.tokens.BlockSequenceStartToken;
import org.yaml.snakeyaml.tokens.DirectiveToken;
import org.yaml.snakeyaml.tokens.DocumentEndToken;
import org.yaml.snakeyaml.tokens.DocumentStartToken;
import org.yaml.snakeyaml.tokens.FlowEntryToken;
import org.yaml.snakeyaml.tokens.FlowMappingEndToken;
import org.yaml.snakeyaml.tokens.FlowMappingStartToken;
import org.yaml.snakeyaml.tokens.FlowSequenceEndToken;
import org.yaml.snakeyaml.tokens.FlowSequenceStartToken;
import org.yaml.snakeyaml.tokens.KeyToken;
import org.yaml.snakeyaml.tokens.ScalarToken;
import org.yaml.snakeyaml.tokens.StreamEndToken;
import org.yaml.snakeyaml.tokens.StreamStartToken;
import org.yaml.snakeyaml.tokens.TagToken;
import org.yaml.snakeyaml.tokens.TagTuple;
import org.yaml.snakeyaml.tokens.Token;
import org.yaml.snakeyaml.tokens.ValueToken;
import org.yaml.snakeyaml.util.ArrayStack;
import org.yaml.snakeyaml.util.UriEncoder;
/**
* <pre>
* Scanner produces tokens of the following types:
* STREAM-START
* STREAM-END
* DIRECTIVE(name, value)
* DOCUMENT-START
* DOCUMENT-END
* BLOCK-SEQUENCE-START
* BLOCK-MAPPING-START
* BLOCK-END
* FLOW-SEQUENCE-START
* FLOW-MAPPING-START
* FLOW-SEQUENCE-END
* FLOW-MAPPING-END
* BLOCK-ENTRY
* FLOW-ENTRY
* KEY
* VALUE
* ALIAS(value)
* ANCHOR(value)
* TAG(value)
* SCALAR(value, plain, style)
* Read comments in the Scanner code for more details.
* </pre>
*/
@SuppressWarnings({ "javadoc" })
public final class ScannerImpl implements Scanner {
/**
* A regular expression matching characters which are not in the hexadecimal set (0-9, A-F, a-f).
*/
private final static Pattern NOT_HEXA = Pattern.compile("[^0-9A-Fa-f]");
/**
* A mapping from an escaped character in the input stream to the character that they should be replaced with.
*
* YAML defines several common and a few uncommon escape sequences.
*
* @see <a href="http://www.yaml.org/spec/current.html#id2517668">4.1.6. Escape Sequences</a>
*/
public final static Map<Character, String> ESCAPE_REPLACEMENTS = new HashMap<Character, String>();
/**
* A mapping from a character to a number of bytes to read-ahead for that escape sequence. These escape sequences are used to handle
* unicode escaping in the following formats, where H is a hexadecimal character:
*
* <pre>
* \xHH : escaped 8-bit Unicode character
* \uHHHH : escaped 16-bit Unicode character
* \UHHHHHHHH : escaped 32-bit Unicode character
* </pre>
*
* @see <a href="http://yaml.org/spec/1.1/current.html#id872840">5.6. Escape Sequences</a>
*/
public final static Map<Character, Integer> ESCAPE_CODES = new HashMap<Character, Integer>();
static {
// ASCII null
ESCAPE_REPLACEMENTS.put(Character.valueOf('0'), "\0");
// ASCII bell
ESCAPE_REPLACEMENTS.put(Character.valueOf('a'), "\u0007");
// ASCII backspace
ESCAPE_REPLACEMENTS.put(Character.valueOf('b'), "\u0008");
// ASCII horizontal tab
ESCAPE_REPLACEMENTS.put(Character.valueOf('t'), "\u0009");
// ASCII newline (line feed; \n maps to 0x0A)
ESCAPE_REPLACEMENTS.put(Character.valueOf('n'), "\n");
// ASCII vertical tab
ESCAPE_REPLACEMENTS.put(Character.valueOf('v'), "\u000B");
// ASCII form-feed
ESCAPE_REPLACEMENTS.put(Character.valueOf('f'), "\u000C");
// carriage-return (\r maps to 0x0D)
ESCAPE_REPLACEMENTS.put(Character.valueOf('r'), "\r");
// ASCII escape character (Esc)
ESCAPE_REPLACEMENTS.put(Character.valueOf('e'), "\u001B");
// ASCII space
ESCAPE_REPLACEMENTS.put(Character.valueOf(' '), "\u0020");
// ASCII double-quote
ESCAPE_REPLACEMENTS.put(Character.valueOf('"'), "\"");
// ASCII backslash
ESCAPE_REPLACEMENTS.put(Character.valueOf('\\'), "\\");
// Unicode next line
ESCAPE_REPLACEMENTS.put(Character.valueOf('N'), "\u0085");
// Unicode non-breaking-space
ESCAPE_REPLACEMENTS.put(Character.valueOf('_'), "\u00A0");
// Unicode line-separator
ESCAPE_REPLACEMENTS.put(Character.valueOf('L'), "\u2028");
// Unicode paragraph separator
ESCAPE_REPLACEMENTS.put(Character.valueOf('P'), "\u2029");
// 8-bit Unicode
ESCAPE_CODES.put(Character.valueOf('x'), 2);
// 16-bit Unicode
ESCAPE_CODES.put(Character.valueOf('u'), 4);
// 32-bit Unicode (Supplementary characters are supported)
ESCAPE_CODES.put(Character.valueOf('U'), 8);
}
private final StreamReader reader;
// Had we reached the end of the stream?
private boolean done = false;
// The number of unclosed '{' and '['. `flow_level == 0` means block
// context.
private int flowLevel = 0;
// List of processed tokens that are not yet emitted.
private List<Token> tokens;
// Number of tokens that were emitted through the `get_token` method.
private int tokensTaken = 0;
// The current indentation level.
private int indent = -1;
// Past indentation levels.
private ArrayStack<Integer> indents;
// Variables related to simple keys treatment. See PyYAML.
/**
* <pre>
* A simple key is a key that is not denoted by the '?' indicator.
* Example of simple keys:
* ---
* block simple key: value
* ? not a simple key:
* : { flow simple key: value }
* We emit the KEY token before all keys, so when we find a potential
* simple key, we try to locate the corresponding ':' indicator.
* Simple keys should be limited to a single line and 1024 characters.
*
* Can a simple key start at the current position? A simple key may
* start:
* - at the beginning of the line, not counting indentation spaces
* (in block context),
* - after '{', '[', ',' (in the flow context),
* - after '?', ':', '-' (in the block context).
* In the block context, this flag also signifies if a block collection
* may start at the current position.
* </pre>
*/
private boolean allowSimpleKey = true;
/*
* Keep track of possible simple keys. This is a dictionary. The key is
* `flow_level`; there can be no more that one possible simple key for each
* level. The value is a SimpleKey record: (token_number, required, index,
* line, column, mark) A simple key may start with ALIAS, ANCHOR, TAG,
* SCALAR(flow), '[', or '{' tokens.
*/
private Map<Integer, SimpleKey> possibleSimpleKeys;
public ScannerImpl(final StreamReader reader) {
this.reader = reader;
this.tokens = new ArrayList<Token>(100);
this.indents = new ArrayStack<Integer>(10);
// The order in possibleSimpleKeys is kept for nextPossibleSimpleKey()
this.possibleSimpleKeys = new LinkedHashMap<Integer, SimpleKey>();
fetchStreamStart();// Add the STREAM-START token.
}
/**
* Check whether the next token is one of the given types.
*/
@Override
public boolean checkToken(final Token.ID... choices) {
while (needMoreTokens()) {
fetchMoreTokens();
}
if (!this.tokens.isEmpty()) {
if (choices.length == 0) {
return true;
}
// since profiler puts this method on top (it is used a lot), we
// should not use 'foreach' here because of the performance reasons
Token.ID first = this.tokens.get(0).getTokenId();
for (int i = 0; i < choices.length; i++) {
if (first == choices[i]) {
return true;
}
}
}
return false;
}
/**
* Return the next token, but do not delete it from the queue.
*/
@Override
public Token peekToken() {
while (needMoreTokens()) {
fetchMoreTokens();
}
return this.tokens.get(0);
}
/**
* Return the next token, removing it from the queue.
*/
@Override
public Token getToken() {
if (!this.tokens.isEmpty()) {
this.tokensTaken++;
return this.tokens.remove(0);
}
return null;
}
// Private methods.
/**
* Returns true if more tokens should be scanned.
*/
private boolean needMoreTokens() {
// If we are done, we do not require more tokens.
if (this.done) {
return false;
}
// If we aren't done, but we have no tokens, we need to scan more.
if (this.tokens.isEmpty()) {
return true;
}
// The current token may be a potential simple key, so we
// need to look further.
stalePossibleSimpleKeys();
return nextPossibleSimpleKey() == this.tokensTaken;
}
/**
* Fetch one or more tokens from the StreamReader.
*/
private void fetchMoreTokens() {
// Eat whitespaces and comments until we reach the next token.
scanToNextToken();
// Remove obsolete possible simple keys.
stalePossibleSimpleKeys();
// Compare the current indentation and column. It may add some tokens
// and decrease the current indentation level.
unwindIndent(reader.getColumn());
// Peek the next character, to decide what the next group of tokens
// will look like.
char ch = reader.peek();
switch (ch) {
case '\0':
// Is it the end of stream?
fetchStreamEnd();
return;
case '%':
// Is it a directive?
if (checkDirective()) {
fetchDirective();
return;
}
break;
case '-':
// Is it the document start?
if (checkDocumentStart()) {
fetchDocumentStart();
return;
// Is it the block entry indicator?
} else if (checkBlockEntry()) {
fetchBlockEntry();
return;
}
break;
case '.':
// Is it the document end?
if (checkDocumentEnd()) {
fetchDocumentEnd();
return;
}
break;
// TODO support for BOM within a stream. (not implemented in PyYAML)
case '[':
// Is it the flow sequence start indicator?
fetchFlowSequenceStart();
return;
case '{':
// Is it the flow mapping start indicator?
fetchFlowMappingStart();
return;
case ']':
// Is it the flow sequence end indicator?
fetchFlowSequenceEnd();
return;
case '}':
// Is it the flow mapping end indicator?
fetchFlowMappingEnd();
return;
case ',':
// Is it the flow entry indicator?
fetchFlowEntry();
return;
// see block entry indicator above
case '?':
// Is it the key indicator?
if (checkKey()) {
fetchKey();
return;
}
break;
case ':':
// Is it the value indicator?
if (checkValue()) {
fetchValue();
return;
}
break;
case '*':
// Is it an alias?
fetchAlias();
return;
case '&':
// Is it an anchor?
fetchAnchor();
return;
case '!':
// Is it a tag?
fetchTag();
return;
case '|':
// Is it a literal scalar?
if (this.flowLevel == 0) {
fetchLiteral();
return;
}
break;
case '>':
// Is it a folded scalar?
if (this.flowLevel == 0) {
fetchFolded();
return;
}
break;
case '\'':
// Is it a single quoted scalar?
fetchSingle();
return;
case '"':
// Is it a double quoted scalar?
fetchDouble();
return;
}
// It must be a plain scalar then.
if (checkPlain()) {
fetchPlain();
return;
}
// No? It's an error. Let's produce a nice error message.We do this by
// converting escaped characters into their escape sequences. This is a
// backwards use of the ESCAPE_REPLACEMENTS map.
String chRepresentation = String.valueOf(ch);
for (Character s : ESCAPE_REPLACEMENTS.keySet()) {
String v = ESCAPE_REPLACEMENTS.get(s);
if (v.equals(chRepresentation)) {
chRepresentation = "\\" + s;// ' ' -> '\t'
break;
}
}
if (ch == '\t')
chRepresentation += "(TAB)";
String text = String.format("found character %s '%s' that cannot start any token. (Do not use %s for indentation)", ch,
chRepresentation, chRepresentation);
throw new ScannerException("while scanning for the next token", null, text, reader.getMark());
}
// Simple keys treatment.
/**
* Return the number of the nearest possible simple key. Actually we don't need to loop through the whole dictionary.
*/
private int nextPossibleSimpleKey() {
/*
* the implementation is not as in PyYAML. Because
* this.possibleSimpleKeys is ordered we can simply take the first key
*/
if (!this.possibleSimpleKeys.isEmpty()) {
return this.possibleSimpleKeys.values().iterator().next().getTokenNumber();
}
return -1;
}
/**
* <pre>
* Remove entries that are no longer possible simple keys. According to
* the YAML specification, simple keys
* - should be limited to a single line,
* - should be no longer than 1024 characters.
* Disabling this procedure will allow simple keys of any length and
* height (may cause problems if indentation is broken though).
* </pre>
*/
private void stalePossibleSimpleKeys() {
if (!this.possibleSimpleKeys.isEmpty()) {
for (Iterator<SimpleKey> iterator = this.possibleSimpleKeys.values().iterator(); iterator.hasNext();) {
SimpleKey key = iterator.next();
if ((key.getLine() != reader.getLine()) || (reader.getIndex() - key.getIndex() > 1024)) {
// If the key is not on the same line as the current
// position OR the difference in column between the token
// start and the current position is more than the maximum
// simple key length, then this cannot be a simple key.
if (key.isRequired()) {
// If the key was required, this implies an error
// condition.
throw new ScannerException("while scanning a simple key", key.getMark(), "could not found expected ':'",
reader.getMark());
}
iterator.remove();
}
}
}
}
/**
* The next token may start a simple key. We check if it's possible and save its position. This function is called for ALIAS, ANCHOR,
* TAG, SCALAR(flow), '[', and '{'.
*/
private void savePossibleSimpleKey() {
// The next token may start a simple key. We check if it's possible
// and save its position. This function is called for
// ALIAS, ANCHOR, TAG, SCALAR(flow), '[', and '{'.
// Check if a simple key is required at the current position.
// A simple key is required if this position is the root flowLevel, AND
// the current indentation level is the same as the last indent-level.
boolean required = ((this.flowLevel == 0) && (this.indent == this.reader.getColumn()));
if (allowSimpleKey || !required) {
// A simple key is required only if it is the first token in the
// current line. Therefore it is always allowed.
} else {
throw new YAMLException("A simple key is required only if it is the first token in the current line");
}
// The next token might be a simple key. Let's save it's number and
// position.
if (this.allowSimpleKey) {
removePossibleSimpleKey();
int tokenNumber = this.tokensTaken + this.tokens.size();
SimpleKey key = new SimpleKey(tokenNumber, required, reader.getIndex(), reader.getLine(), this.reader.getColumn(),
this.reader.getMark());
this.possibleSimpleKeys.put(this.flowLevel, key);
}
}
/**
* Remove the saved possible key position at the current flow level.
*/
private void removePossibleSimpleKey() {
SimpleKey key = possibleSimpleKeys.remove(flowLevel);
if (key != null && key.isRequired()) {
throw new ScannerException("while scanning a simple key", key.getMark(), "could not found expected ':'", reader.getMark());
}
}
// Indentation functions.
/**
* * Handle implicitly ending multiple levels of block nodes by decreased indentation. This function becomes important on lines 4 and 7
* of this example:
*
* <pre>
* 1) book one:
* 2) part one:
* 3) chapter one
* 4) part two:
* 5) chapter one
* 6) chapter two
* 7) book two:
* </pre>
*
* In flow context, tokens should respect indentation. Actually the condition should be `self.indent >= column` according to the
* spec. But this condition will prohibit intuitively correct constructions such as key : { } </pre>
*/
private void unwindIndent(final int col) {
// In the flow context, indentation is ignored. We make the scanner less
// restrictive then specification requires.
if (this.flowLevel != 0) {
return;
}
// In block context, we may need to issue the BLOCK-END tokens.
while (this.indent > col) {
Mark mark = reader.getMark();
this.indent = this.indents.pop();
this.tokens.add(new BlockEndToken(mark, mark));
}
}
/**
* Check if we need to increase indentation.
*/
private boolean addIndent(final int column) {
if (this.indent < column) {
this.indents.push(this.indent);
this.indent = column;
return true;
}
return false;
}
// Fetchers.
/**
* We always add STREAM-START as the first token and STREAM-END as the last token.
*/
private void fetchStreamStart() {
// Read the token.
Mark mark = reader.getMark();
// Add STREAM-START.
Token token = new StreamStartToken(mark, mark);
this.tokens.add(token);
}
private void fetchStreamEnd() {
// Set the current intendation to -1.
unwindIndent(-1);
// Reset simple keys.
removePossibleSimpleKey();
this.allowSimpleKey = false;
this.possibleSimpleKeys.clear();
// Read the token.
Mark mark = reader.getMark();
// Add STREAM-END.
Token token = new StreamEndToken(mark, mark);
this.tokens.add(token);
// The stream is finished.
this.done = true;
}
/**
* Fetch a YAML directive. Directives are presentation details that are interpreted as instructions to the processor. YAML defines two
* kinds of directives, YAML and TAG; all other types are reserved for future use.
*
* @see http://www.yaml.org/spec/1.1/#id864824
*/
private void fetchDirective() {
// Set the current intendation to -1.
unwindIndent(-1);
// Reset simple keys.
removePossibleSimpleKey();
this.allowSimpleKey = false;
// Scan and add DIRECTIVE.
Token tok = scanDirective();
this.tokens.add(tok);
}
/**
* Fetch a document-start token ("---").
*/
private void fetchDocumentStart() {
fetchDocumentIndicator(true);
}
/**
* Fetch a document-end token ("...").
*/
private void fetchDocumentEnd() {
fetchDocumentIndicator(false);
}
/**
* Fetch a document indicator, either "---" for "document-start", or else "..." for "document-end. The type is chosen by the given
* boolean.
*/
private void fetchDocumentIndicator(final boolean isDocumentStart) {
// Set the current intendation to -1.
unwindIndent(-1);
// Reset simple keys. Note that there could not be a block collection
// after '---'.
removePossibleSimpleKey();
this.allowSimpleKey = false;
// Add DOCUMENT-START or DOCUMENT-END.
Mark startMark = reader.getMark();
reader.forward(3);
Mark endMark = reader.getMark();
Token token;
if (isDocumentStart) {
token = new DocumentStartToken(startMark, endMark);
} else {
token = new DocumentEndToken(startMark, endMark);
}
this.tokens.add(token);
}
private void fetchFlowSequenceStart() {
fetchFlowCollectionStart(false);
}
private void fetchFlowMappingStart() {
fetchFlowCollectionStart(true);
}
/**
* Fetch a flow-style collection start, which is either a sequence or a mapping. The type is determined by the given boolean.
*
* A flow-style collection is in a format similar to JSON. Sequences are started by '[' and ended by ']'; mappings are started by '{'
* and ended by '}'.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*
* @param isMappingStart
*/
private void fetchFlowCollectionStart(final boolean isMappingStart) {
// '[' and '{' may start a simple key.
savePossibleSimpleKey();
// Increase the flow level.
this.flowLevel++;
// Simple keys are allowed after '[' and '{'.
this.allowSimpleKey = true;
// Add FLOW-SEQUENCE-START or FLOW-MAPPING-START.
Mark startMark = reader.getMark();
reader.forward(1);
Mark endMark = reader.getMark();
Token token;
if (isMappingStart) {
token = new FlowMappingStartToken(startMark, endMark);
} else {
token = new FlowSequenceStartToken(startMark, endMark);
}
this.tokens.add(token);
}
private void fetchFlowSequenceEnd() {
fetchFlowCollectionEnd(false);
}
private void fetchFlowMappingEnd() {
fetchFlowCollectionEnd(true);
}
/**
* Fetch a flow-style collection end, which is either a sequence or a mapping. The type is determined by the given boolean.
*
* A flow-style collection is in a format similar to JSON. Sequences are started by '[' and ended by ']'; mappings are started by '{'
* and ended by '}'.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchFlowCollectionEnd(final boolean isMappingEnd) {
// Reset possible simple key on the current level.
removePossibleSimpleKey();
// Decrease the flow level.
this.flowLevel--;
// No simple keys after ']' or '}'.
this.allowSimpleKey = false;
// Add FLOW-SEQUENCE-END or FLOW-MAPPING-END.
Mark startMark = reader.getMark();
reader.forward();
Mark endMark = reader.getMark();
Token token;
if (isMappingEnd) {
token = new FlowMappingEndToken(startMark, endMark);
} else {
token = new FlowSequenceEndToken(startMark, endMark);
}
this.tokens.add(token);
}
/**
* Fetch an entry in the flow style. Flow-style entries occur either immediately after the start of a collection, or else after a comma.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchFlowEntry() {
// Simple keys are allowed after ','.
this.allowSimpleKey = true;
// Reset possible simple key on the current level.
removePossibleSimpleKey();
// Add FLOW-ENTRY.
Mark startMark = reader.getMark();
reader.forward();
Mark endMark = reader.getMark();
Token token = new FlowEntryToken(startMark, endMark);
this.tokens.add(token);
}
/**
* Fetch an entry in the block style.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchBlockEntry() {
// Block context needs additional checks.
if (this.flowLevel == 0) {
// Are we allowed to start a new entry?
if (!this.allowSimpleKey) {
throw new ScannerException(null, null, "sequence entries are not allowed here", reader.getMark());
}
// We may need to add BLOCK-SEQUENCE-START.
if (addIndent(this.reader.getColumn())) {
Mark mark = reader.getMark();
this.tokens.add(new BlockSequenceStartToken(mark, mark));
}
} else {
// It's an error for the block entry to occur in the flow
// context,but we let the parser detect this.
}
// Simple keys are allowed after '-'.
this.allowSimpleKey = true;
// Reset possible simple key on the current level.
removePossibleSimpleKey();
// Add BLOCK-ENTRY.
Mark startMark = reader.getMark();
reader.forward();
Mark endMark = reader.getMark();
Token token = new BlockEntryToken(startMark, endMark);
this.tokens.add(token);
}
/**
* Fetch a key in a block-style mapping.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchKey() {
// Block context needs additional checks.
if (this.flowLevel == 0) {
// Are we allowed to start a key (not necessary a simple)?
if (!this.allowSimpleKey) {
throw new ScannerException(null, null, "mapping keys are not allowed here", reader.getMark());
}
// We may need to add BLOCK-MAPPING-START.
if (addIndent(this.reader.getColumn())) {
Mark mark = reader.getMark();
this.tokens.add(new BlockMappingStartToken(mark, mark));
}
}
// Simple keys are allowed after '?' in the block context.
this.allowSimpleKey = this.flowLevel == 0;
// Reset possible simple key on the current level.
removePossibleSimpleKey();
// Add KEY.
Mark startMark = reader.getMark();
reader.forward();
Mark endMark = reader.getMark();
Token token = new KeyToken(startMark, endMark);
this.tokens.add(token);
}
/**
* Fetch a value in a block-style mapping.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchValue() {
// Do we determine a simple key?
SimpleKey key = this.possibleSimpleKeys.remove(this.flowLevel);
if (key != null) {
// Add KEY.
this.tokens.add(key.getTokenNumber() - this.tokensTaken, new KeyToken(key.getMark(), key.getMark()));
// If this key starts a new block mapping, we need to add
// BLOCK-MAPPING-START.
if (this.flowLevel == 0) {
if (addIndent(key.getColumn())) {
this.tokens.add(key.getTokenNumber() - this.tokensTaken, new BlockMappingStartToken(key.getMark(), key.getMark()));
}
}
// There cannot be two simple keys one after another.
this.allowSimpleKey = false;
} else {// It must be a part of a complex key.
// Block context needs additional checks.Do we really need them?
// They
// will be catched by the parser anyway.)
if (this.flowLevel == 0) {
// We are allowed to start a complex value if and only if we can
// start a simple key.
if (!this.allowSimpleKey) {
throw new ScannerException(null, null, "mapping values are not allowed here", reader.getMark());
}
}
// If this value starts a new block mapping, we need to add
// BLOCK-MAPPING-START. It will be detected as an error later by
// the parser.
if (flowLevel == 0) {
if (addIndent(reader.getColumn())) {
Mark mark = reader.getMark();
this.tokens.add(new BlockMappingStartToken(mark, mark));
}
}
// Simple keys are allowed after ':' in the block context.
allowSimpleKey = (flowLevel == 0);
// Reset possible simple key on the current level.
removePossibleSimpleKey();
}
// Add VALUE.
Mark startMark = reader.getMark();
reader.forward();
Mark endMark = reader.getMark();
Token token = new ValueToken(startMark, endMark);
this.tokens.add(token);
}
/**
* Fetch an alias, which is a reference to an anchor. Aliases take the format:
*
* <pre>
* *(anchor name)
* </pre>
*
* @see http://www.yaml.org/spec/1.1/#id863390
*/
private void fetchAlias() {
// ALIAS could be a simple key.
savePossibleSimpleKey();
// No simple keys after ALIAS.
this.allowSimpleKey = false;
// Scan and add ALIAS.
Token tok = scanAnchor(false);
this.tokens.add(tok);
}
/**
* Fetch an anchor. Anchors take the form:
*
* <pre>
* &(anchor name)
* </pre>
*
* @see http://www.yaml.org/spec/1.1/#id863390
*/
private void fetchAnchor() {
// ANCHOR could start a simple key.
savePossibleSimpleKey();
// No simple keys after ANCHOR.
this.allowSimpleKey = false;
// Scan and add ANCHOR.
Token tok = scanAnchor(true);
this.tokens.add(tok);
}
/**
* Fetch a tag. Tags take a complex form.
*
* @see http://www.yaml.org/spec/1.1/#id861700
*/
private void fetchTag() {
// TAG could start a simple key.
savePossibleSimpleKey();
// No simple keys after TAG.
this.allowSimpleKey = false;
// Scan and add TAG.
Token tok = scanTag();
this.tokens.add(tok);
}
/**
* Fetch a literal scalar, denoted with a vertical-bar. This is the type best used for source code and other content, such as binary
* data, which must be included verbatim.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchLiteral() {
fetchBlockScalar('|');
}
/**
* Fetch a folded scalar, denoted with a greater-than sign. This is the type best used for long content, such as the text of a chapter
* or description.
*
* @see http://www.yaml.org/spec/1.1/#id863975
*/
private void fetchFolded() {
fetchBlockScalar('>');
}
/**
* Fetch a block scalar (literal or folded).
*
* @see http://www.yaml.org/spec/1.1/#id863975
*
* @param style
*/
private void fetchBlockScalar(final char style) {
// A simple key may follow a block scalar.
this.allowSimpleKey = true;
// Reset possible simple key on the current level.
removePossibleSimpleKey();
// Scan and add SCALAR.
Token tok = scanBlockScalar(style);
this.tokens.add(tok);
}
/**
* Fetch a single-quoted (') scalar.
*/
private void fetchSingle() {
fetchFlowScalar('\'');
}
/**
* Fetch a double-quoted (") scalar.
*/
private void fetchDouble() {
fetchFlowScalar('"');
}
/**
* Fetch a flow scalar (single- or double-quoted).
*
* @see http://www.yaml.org/spec/1.1/#id863975
*
* @param style
*/
private void fetchFlowScalar(final char style) {
// A flow scalar could be a simple key.
savePossibleSimpleKey();
// No simple keys after flow scalars.
this.allowSimpleKey = false;
// Scan and add SCALAR.
Token tok = scanFlowScalar(style);
this.tokens.add(tok);
}
/**
* Fetch a plain scalar.
*/
private void fetchPlain() {
// A plain scalar could be a simple key.
savePossibleSimpleKey();
// No simple keys after plain scalars. But note that `scan_plain` will
// change this flag if the scan is finished at the beginning of the
// line.
this.allowSimpleKey = false;
// Scan and add SCALAR. May change `allow_simple_key`.
Token tok = scanPlain();
this.tokens.add(tok);
}
// Checkers.
/**
* Returns true if the next thing on the reader is a directive, given that the leading '%' has already been checked.
*
* @see http://www.yaml.org/spec/1.1/#id864824
*/
private boolean checkDirective() {
// DIRECTIVE: ^ '%' ...
// The '%' indicator is already checked.
return reader.getColumn() == 0;
}
/**
* Returns true if the next thing on the reader is a document-start ("---"). A document-start is always followed immediately by a new
* line.
*/
private boolean checkDocumentStart() {
// DOCUMENT-START: ^ '---' (' '|'\n')
if (reader.getColumn() == 0) {
if ("---".equals(reader.prefix(3)) && Constant.NULL_BL_T_LINEBR.has(reader.peek(3))) {
return true;
}
}
return false;
}
/**
* Returns true if the next thing on the reader is a document-end ("..."). A document-end is always followed immediately by a new line.
*/
private boolean checkDocumentEnd() {
// DOCUMENT-END: ^ '...' (' '|'\n')
if (reader.getColumn() == 0) {
if ("...".equals(reader.prefix(3)) && Constant.NULL_BL_T_LINEBR.has(reader.peek(3))) {
return true;
}
}
return false;
}
/**
* Returns true if the next thing on the reader is a block token.
*/
private boolean checkBlockEntry() {
// BLOCK-ENTRY: '-' (' '|'\n')
return Constant.NULL_BL_T_LINEBR.has(reader.peek(1));
}
/**
* Returns true if the next thing on the reader is a key token.
*/
private boolean checkKey() {
// KEY(flow context): '?'
if (this.flowLevel != 0) {
return true;
} else {
// KEY(block context): '?' (' '|'\n')
return Constant.NULL_BL_T_LINEBR.has(reader.peek(1));
}
}
/**
* Returns true if the next thing on the reader is a value token.
*/
private boolean checkValue() {
// VALUE(flow context): ':'
if (flowLevel != 0) {
return true;
} else {
// VALUE(block context): ':' (' '|'\n')
return Constant.NULL_BL_T_LINEBR.has(reader.peek(1));
}
}
/**
* Returns true if the next thing on the reader is a plain token.
*/
private boolean checkPlain() {
/**
* <pre>
* A plain scalar may start with any non-space character except:
* '-', '?', ':', ',', '[', ']', '{', '}',
* '#', '&', '*', '!', '|', '>', '\'', '\"',
* '%', '@', '`'.
*
* It may also start with
* '-', '?', ':'
* if it is followed by a non-space character.
*
* Note that we limit the last rule to the block context (except the
* '-' character) because we want the flow context to be space
* independent.
* </pre>
*/
char ch = reader.peek();
// If the next char is NOT one of the forbidden chars above or
// whitespace, then this is the start of a plain scalar.
return Constant.NULL_BL_T_LINEBR.hasNo(ch, "-?:,[]{}#&*!|>\'\"%@`")
|| (Constant.NULL_BL_T_LINEBR.hasNo(reader.peek(1)) && (ch == '-' || (this.flowLevel == 0 && "?:".indexOf(ch) != -1)));
}
// Scanners.
/**
* <pre>
* We ignore spaces, line breaks and comments.
* If we find a line break in the block context, we set the flag
* `allow_simple_key` on.
* The byte order mark is stripped if it's the first character in the
* stream. We do not yet support BOM inside the stream as the
* specification requires. Any such mark will be considered as a part
* of the document.
* TODO: We need to make tab handling rules more sane. A good rule is
* Tabs cannot precede tokens
* BLOCK-SEQUENCE-START, BLOCK-MAPPING-START, BLOCK-END,
* KEY(block), VALUE(block), BLOCK-ENTRY
* So the checking code is
* if <TAB>:
* self.allow_simple_keys = False
* We also need to add the check for `allow_simple_keys == True` to
* `unwind_indent` before issuing BLOCK-END.
* Scanners for block, flow, and plain scalars need to be modified.
* </pre>
*/
private void scanToNextToken() {
// If there is a byte order mark (BOM) at the beginning of the stream,
// forward past it.
if (reader.getIndex() == 0 && reader.peek() == '\uFEFF') {
reader.forward();
}
boolean found = false;
while (!found) {
int ff = 0;
// Peek ahead until we find the first non-space character, then
// move forward directly to that character.
while (reader.peek(ff) == ' ') {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
// If the character we have skipped forward to is a comment (#),
// then peek ahead until we find the next end of line. YAML
// comments are from a # to the next new-line. We then forward
// past the comment.
if (reader.peek() == '#') {
ff = 0;
while (Constant.NULL_OR_LINEBR.hasNo(reader.peek(ff))) {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
}
// If we scanned a line break, then (depending on flow level),
// simple keys may be allowed.
if (scanLineBreak().length() != 0) {// found a line-break
if (this.flowLevel == 0) {
// Simple keys are allowed at flow-level 0 after a line
// break
this.allowSimpleKey = true;
}
} else {
found = true;
}
}
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private Token scanDirective() {
// See the specification for details.
Mark startMark = reader.getMark();
Mark endMark;
reader.forward();
String name = scanDirectiveName(startMark);
List<?> value = null;
if ("YAML".equals(name)) {
value = scanYamlDirectiveValue(startMark);
endMark = reader.getMark();
} else if ("TAG".equals(name)) {
value = scanTagDirectiveValue(startMark);
endMark = reader.getMark();
} else {
endMark = reader.getMark();
int ff = 0;
while (Constant.NULL_OR_LINEBR.hasNo(reader.peek(ff))) {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
}
scanDirectiveIgnoredLine(startMark);
return new DirectiveToken(name, value, startMark, endMark);
}
/**
* Scan a directive name. Directive names are a series of non-space characters.
*
* @see http://www.yaml.org/spec/1.1/#id895217
*/
private String scanDirectiveName(final Mark startMark) {
// See the specification for details.
int length = 0;
// A Directive-name is a sequence of alphanumeric characters
// (a-z,A-Z,0-9). We scan until we find something that isn't.
// FIXME this disagrees with the specification.
char ch = reader.peek(length);
while (Constant.ALPHA.has(ch)) {
length++;
ch = reader.peek(length);
}
// If the name would be empty, an error occurs.
if (length == 0) {
throw new ScannerException("while scanning a directive", startMark, "expected alphabetic or numeric character, but found " + ch
+ "(" + ((int) ch) + ")", reader.getMark());
}
String value = reader.prefixForward(length);
ch = reader.peek();
if (Constant.NULL_BL_LINEBR.hasNo(ch)) {
throw new ScannerException("while scanning a directive", startMark, "expected alphabetic or numeric character, but found " + ch
+ "(" + ((int) ch) + ")", reader.getMark());
}
return value;
}
private List<Integer> scanYamlDirectiveValue(final Mark startMark) {
// See the specification for details.
while (reader.peek() == ' ') {
reader.forward();
}
Integer major = scanYamlDirectiveNumber(startMark);
if (reader.peek() != '.') {
throw new ScannerException("while scanning a directive", startMark, "expected a digit or '.', but found " + reader.peek() + "("
+ ((int) reader.peek()) + ")", reader.getMark());
}
reader.forward();
Integer minor = scanYamlDirectiveNumber(startMark);
if (Constant.NULL_BL_LINEBR.hasNo(reader.peek())) {
throw new ScannerException("while scanning a directive", startMark, "expected a digit or ' ', but found " + reader.peek() + "("
+ ((int) reader.peek()) + ")", reader.getMark());
}
List<Integer> result = new ArrayList<Integer>(2);
result.add(major);
result.add(minor);
return result;
}
/**
* Read a %YAML directive number: this is either the major or the minor part. Stop reading at a non-digit character (usually either '.'
* or '\n').
*
* @see http://www.yaml.org/spec/1.1/#id895631
* @see http://www.yaml.org/spec/1.1/#ns-dec-digit
*/
private Integer scanYamlDirectiveNumber(final Mark startMark) {
// See the specification for details.
char ch = reader.peek();
if (!Character.isDigit(ch)) {
throw new ScannerException("while scanning a directive", startMark, "expected a digit, but found " + ch + "(" + ((int) ch)
+ ")", reader.getMark());
}
int length = 0;
while (Character.isDigit(reader.peek(length))) {
length++;
}
Integer value = Integer.parseInt(reader.prefixForward(length));
return value;
}
/**
* <p>
* Read a %TAG directive value:
*
* <pre>
* s-ignored-space+ c-tag-handle s-ignored-space+ ns-tag-prefix s-l-comments
* </pre>
*
* </p>
*
* @see http://www.yaml.org/spec/1.1/#id896044
*/
private List<String> scanTagDirectiveValue(final Mark startMark) {
// See the specification for details.
while (reader.peek() == ' ') {
reader.forward();
}
String handle = scanTagDirectiveHandle(startMark);
while (reader.peek() == ' ') {
reader.forward();
}
String prefix = scanTagDirectivePrefix(startMark);
List<String> result = new ArrayList<String>(2);
result.add(handle);
result.add(prefix);
return result;
}
/**
* Scan a %TAG directive's handle. This is YAML's c-tag-handle.
*
* @see http://www.yaml.org/spec/1.1/#id896876
* @param startMark
* @return
*/
private String scanTagDirectiveHandle(final Mark startMark) {
// See the specification for details.
String value = scanTagHandle("directive", startMark);
char ch = reader.peek();
if (ch != ' ') {
throw new ScannerException("while scanning a directive", startMark,
"expected ' ', but found " + reader.peek() + "(" + ch + ")", reader.getMark());
}
return value;
}
/**
* Scan a %TAG directive's prefix. This is YAML's ns-tag-prefix.
*
* @see http://www.yaml.org/spec/1.1/#ns-tag-prefix
*/
private String scanTagDirectivePrefix(final Mark startMark) {
// See the specification for details.
String value = scanTagUri("directive", startMark);
if (Constant.NULL_BL_LINEBR.hasNo(reader.peek())) {
throw new ScannerException("while scanning a directive", startMark, "expected ' ', but found " + reader.peek() + "("
+ ((int) reader.peek()) + ")", reader.getMark());
}
return value;
}
private String scanDirectiveIgnoredLine(final Mark startMark) {
// See the specification for details.
int ff = 0;
while (reader.peek(ff) == ' ') {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
if (reader.peek() == '#') {
ff = 0;
while (Constant.NULL_OR_LINEBR.hasNo(reader.peek(ff))) {
ff++;
}
reader.forward(ff);
}
char ch = reader.peek();
String lineBreak = scanLineBreak();
if (lineBreak.length() == 0 && ch != '\0') {
throw new ScannerException("while scanning a directive", startMark, "expected a comment or a line break, but found " + ch + "("
+ ((int) ch) + ")", reader.getMark());
}
return lineBreak;
}
/**
* <pre>
* The specification does not restrict characters for anchors and
* aliases. This may lead to problems, for instance, the document:
* [ *alias, value ]
* can be interpreted in two ways, as
* [ "value" ]
* and
* [ *alias , "value" ]
* Therefore we restrict aliases to numbers and ASCII letters.
* </pre>
*/
private Token scanAnchor(final boolean isAnchor) {
Mark startMark = reader.getMark();
char indicator = reader.peek();
String name = indicator == '*' ? "alias" : "anchor";
reader.forward();
int length = 0;
char ch = reader.peek(length);
while (Constant.ALPHA.has(ch)) {
length++;
ch = reader.peek(length);
}
if (length == 0) {
throw new ScannerException("while scanning an " + name, startMark,
"expected alphabetic or numeric character, but found but found " + ch, reader.getMark());
}
String value = reader.prefixForward(length);
ch = reader.peek();
if (Constant.NULL_BL_T_LINEBR.hasNo(ch, "?:,]}%@`")) {
throw new ScannerException("while scanning an " + name, startMark, "expected alphabetic or numeric character, but found " + ch
+ "(" + ((int) reader.peek()) + ")", reader.getMark());
}
Mark endMark = reader.getMark();
Token tok;
if (isAnchor) {
tok = new AnchorToken(value, startMark, endMark);
} else {
tok = new AliasToken(value, startMark, endMark);
}
return tok;
}
/**
* <p>
* Scan a Tag property. A Tag property may be specified in one of three ways: c-verbatim-tag, c-ns-shorthand-tag, or
* c-ns-non-specific-tag
* </p>
*
* <p>
* c-verbatim-tag takes the form !<ns-uri-char+> and must be delivered verbatim (as-is) to the application. In particular,
* verbatim tags are not subject to tag resolution.
* </p>
*
* <p>
* c-ns-shorthand-tag is a valid tag handle followed by a non-empty suffix. If the tag handle is a c-primary-tag-handle ('!') then the
* suffix must have all exclamation marks properly URI-escaped (%21); otherwise, the string will look like a named tag handle: !foo!bar
* would be interpreted as (handle="!foo!", suffix="bar").
* </p>
*
* <p>
* c-ns-non-specific-tag is always a lone '!'; this is only useful for plain scalars, where its specification means that the scalar MUST
* be resolved to have type tag:yaml.org,2002:str.
* </p>
*
* TODO SnakeYaml incorrectly ignores c-ns-non-specific-tag right now.
*
* @see http://www.yaml.org/spec/1.1/#id900262
*
* TODO Note that this method does not enforce rules about local versus global tags!
*/
private Token scanTag() {
// See the specification for details.
Mark startMark = reader.getMark();
// Determine the type of tag property based on the first character
// encountered
char ch = reader.peek(1);
String handle = null;
String suffix = null;
// Verbatim tag! (c-verbatim-tag)
if (ch == '<') {
// Skip the exclamation mark and >, then read the tag suffix (as
// a URI).
reader.forward(2);
suffix = scanTagUri("tag", startMark);
if (reader.peek() != '>') {
// If there are any characters between the end of the tag-suffix
// URI and the closing >, then an error has occurred.
throw new ScannerException("while scanning a tag", startMark, "expected '>', but found '" + reader.peek() + "' ("
+ ((int) reader.peek()) + ")", reader.getMark());
}
reader.forward();
} else if (Constant.NULL_BL_T_LINEBR.has(ch)) {
// A NUL, blank, tab, or line-break means that this was a
// c-ns-non-specific tag.
suffix = "!";
reader.forward();
} else {
// Any other character implies c-ns-shorthand-tag type.
// Look ahead in the stream to determine whether this tag property
// is of the form !foo or !foo!bar.
int length = 1;
boolean useHandle = false;
while (Constant.NULL_BL_LINEBR.hasNo(ch)) {
if (ch == '!') {
useHandle = true;
break;
}
length++;
ch = reader.peek(length);
}
handle = "!";
// If we need to use a handle, scan it in; otherwise, the handle is
// presumed to be '!'.
if (useHandle) {
handle = scanTagHandle("tag", startMark);
} else {
handle = "!";
reader.forward();
}
suffix = scanTagUri("tag", startMark);
}
ch = reader.peek();
// Check that the next character is allowed to follow a tag-property;
// if it is not, raise the error.
if (Constant.NULL_BL_LINEBR.hasNo(ch)) {
throw new ScannerException("while scanning a tag", startMark, "expected ' ', but found '" + ch + "' (" + ((int) ch) + ")",
reader.getMark());
}
TagTuple value = new TagTuple(handle, suffix);
Mark endMark = reader.getMark();
return new TagToken(value, startMark, endMark);
}
private Token scanBlockScalar(final char style) {
// See the specification for details.
boolean folded;
// Depending on the given style, we determine whether the scalar is
// folded ('>') or literal ('|')
if (style == '>') {
folded = true;
} else {
folded = false;
}
StringBuilder chunks = new StringBuilder();
Mark startMark = reader.getMark();
// Scan the header.
reader.forward();
Chomping chompi = scanBlockScalarIndicators(startMark);
int increment = chompi.getIncrement();
scanBlockScalarIgnoredLine(startMark);
// Determine the indentation level and go to the first non-empty line.
int minIndent = this.indent + 1;
if (minIndent < 1) {
minIndent = 1;
}
String breaks = null;
int maxIndent = 0;
int indent = 0;
Mark endMark;
if (increment == -1) {
Object[] brme = scanBlockScalarIndentation();
breaks = (String) brme[0];
maxIndent = ((Integer) brme[1]).intValue();
endMark = (Mark) brme[2];
indent = Math.max(minIndent, maxIndent);
} else {
indent = minIndent + increment - 1;
Object[] brme = scanBlockScalarBreaks(indent);
breaks = (String) brme[0];
endMark = (Mark) brme[1];
}
String lineBreak = "";
// Scan the inner part of the block scalar.
while (this.reader.getColumn() == indent && reader.peek() != '\0') {
chunks.append(breaks);
boolean leadingNonSpace = " \t".indexOf(reader.peek()) == -1;
int length = 0;
while (Constant.NULL_OR_LINEBR.hasNo(reader.peek(length))) {
length++;
}
chunks.append(reader.prefixForward(length));
lineBreak = scanLineBreak();
Object[] brme = scanBlockScalarBreaks(indent);
breaks = (String) brme[0];
endMark = (Mark) brme[1];
if (this.reader.getColumn() == indent && reader.peek() != '\0') {
// Unfortunately, folding rules are ambiguous.
//
// This is the folding according to the specification:
if (folded && "\n".equals(lineBreak) && leadingNonSpace && " \t".indexOf(reader.peek()) == -1) {
if (breaks.length() == 0) {
chunks.append(" ");
}
} else {
chunks.append(lineBreak);
}
// Clark Evans's interpretation (also in the spec examples) not
// imported from PyYAML
} else {
break;
}
}
// Chomp the tail.
if (chompi.chompTailIsNotFalse()) {
chunks.append(lineBreak);
}
if (chompi.chompTailIsTrue()) {
chunks.append(breaks);
}
// We are done.
return new ScalarToken(chunks.toString(), false, startMark, endMark, style);
}
/**
* Scan a block scalar indicator. The block scalar indicator includes two optional components, which may appear in either order.
*
* A block indentation indicator is a non-zero digit describing the indentation level of the block scalar to follow. This indentation is
* an additional number of spaces relative to the current indentation level.
*
* A block chomping indicator is a + or -, selecting the chomping mode away from the default (clip) to either -(strip) or +(keep).
*
* @see http://www.yaml.org/spec/1.1/#id868988
* @see http://www.yaml.org/spec/1.1/#id927035
* @see http://www.yaml.org/spec/1.1/#id927557
*/
private Chomping scanBlockScalarIndicators(final Mark startMark) {
// See the specification for details.
Boolean chomping = null;
int increment = -1;
char ch = reader.peek();
if (ch == '-' || ch == '+') {
if (ch == '+') {
chomping = Boolean.TRUE;
} else {
chomping = Boolean.FALSE;
}
reader.forward();
ch = reader.peek();
if (Character.isDigit(ch)) {
increment = Integer.parseInt(String.valueOf(ch));
if (increment == 0) {
throw new ScannerException("while scanning a block scalar", startMark,
"expected indentation indicator in the range 1-9, but found 0", reader.getMark());
}
reader.forward();
}
} else if (Character.isDigit(ch)) {
increment = Integer.parseInt(String.valueOf(ch));
if (increment == 0) {
throw new ScannerException("while scanning a block scalar", startMark,
"expected indentation indicator in the range 1-9, but found 0", reader.getMark());
}
reader.forward();
ch = reader.peek();
if (ch == '-' || ch == '+') {
if (ch == '+') {
chomping = Boolean.TRUE;
} else {
chomping = Boolean.FALSE;
}
reader.forward();
}
}
ch = reader.peek();
if (Constant.NULL_BL_LINEBR.hasNo(ch)) {
throw new ScannerException("while scanning a block scalar", startMark,
"expected chomping or indentation indicators, but found " + ch, reader.getMark());
}
return new Chomping(chomping, increment);
}
/**
* Scan to the end of the line after a block scalar has been scanned; the only things that are permitted at this time are comments and
* spaces.
*/
private String scanBlockScalarIgnoredLine(final Mark startMark) {
// See the specification for details.
int ff = 0;
// Forward past any number of trailing spaces
while (reader.peek(ff) == ' ') {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
// If a comment occurs, scan to just before the end of line.
if (reader.peek() == '#') {
ff = 0;
while (Constant.NULL_OR_LINEBR.hasNo(reader.peek(ff))) {
ff++;
}
if (ff > 0) {
reader.forward(ff);
}
}
// If the next character is not a null or line break, an error has
// occurred.
char ch = reader.peek();
String lineBreak = scanLineBreak();
if (lineBreak.length() == 0 && ch != '\0') {
throw new ScannerException("while scanning a block scalar", startMark, "expected a comment or a line break, but found " + ch,
reader.getMark());
}
return lineBreak;
}
/**
* Scans for the indentation of a block scalar implicitly. This mechanism is used only if the block did not explicitly state an
* indentation to be used.
*
* @see http://www.yaml.org/spec/1.1/#id927035
*/
private Object[] scanBlockScalarIndentation() {
// See the specification for details.
StringBuilder chunks = new StringBuilder();
int maxIndent = 0;
Mark endMark = reader.getMark();
// Look ahead some number of lines until the first non-blank character
// occurs; the determined indentation will be the maximum number of
// leading spaces on any of these lines.
while (Constant.LINEBR.has(reader.peek(), " \r")) {
if (reader.peek() != ' ') {
// If the character isn't a space, it must be some kind of
// line-break; scan the line break and track it.
chunks.append(scanLineBreak());
endMark = reader.getMark();
} else {
// If the character is a space, move forward to the next
// character; if we surpass our previous maximum for indent
// level, update that too.
reader.forward();
if (this.reader.getColumn() > maxIndent) {
maxIndent = reader.getColumn();
}
}
}
// Pass several results back together.
return new Object[] { chunks.toString(), maxIndent, endMark };
}
private Object[] scanBlockScalarBreaks(final int indent) {
// See the specification for details.
StringBuilder chunks = new StringBuilder();
Mark endMark = reader.getMark();
int ff = 0;
int col = this.reader.getColumn();
// Scan for up to the expected indentation-level of spaces, then move
// forward past that amount.
while (col < indent && reader.peek(ff) == ' ') {
ff++;
col++;
}
if (ff > 0) {
reader.forward(ff);
}
// Consume one or more line breaks followed by any amount of spaces,
// until we find something that isn't a line-break.
String lineBreak = null;
while ((lineBreak = scanLineBreak()).length() != 0) {
chunks.append(lineBreak);
endMark = reader.getMark();
// Scan past up to (indent) spaces on the next line, then forward
// past them.
ff = 0;
col = this.reader.getColumn();
while (col < indent && reader.peek(ff) == ' ') {
ff++;
col++;
}
if (ff > 0) {
reader.forward(ff);
}
}
// Return both the assembled intervening string and the end-mark.
return new Object[] { chunks.toString(), endMark };
}
/**
* Scan a flow-style scalar. Flow scalars are presented in one of two forms; first, a flow scalar may be a double-quoted string; second,
* a flow scalar may be a single-quoted string.
*
* @see http://www.yaml.org/spec/1.1/#flow style/syntax
*
* <pre>
* See the specification for details.
* Note that we loose indentation rules for quoted scalars. Quoted
* scalars don't need to adhere indentation because " and ' clearly
* mark the beginning and the end of them. Therefore we are less
* restrictive then the specification requires. We only need to check
* that document separators are not included in scalars.
* </pre>
*/
private Token scanFlowScalar(final char style) {
boolean _double;
// The style will be either single- or double-quoted; we determine this
// by the first character in the entry (supplied)
if (style == '"') {
_double = true;
} else {
_double = false;
}
StringBuilder chunks = new StringBuilder();
Mark startMark = reader.getMark();
char quote = reader.peek();
reader.forward();
chunks.append(scanFlowScalarNonSpaces(_double, startMark));
while (reader.peek() != quote) {
chunks.append(scanFlowScalarSpaces(startMark));
chunks.append(scanFlowScalarNonSpaces(_double, startMark));
}
reader.forward();
Mark endMark = reader.getMark();
return new ScalarToken(chunks.toString(), false, startMark, endMark, style);
}
/**
* Scan some number of flow-scalar non-space characters.
*/
private String scanFlowScalarNonSpaces(final boolean doubleQuoted, final Mark startMark) {
// See the specification for details.
StringBuilder chunks = new StringBuilder();
while (true) {
// Scan through any number of characters which are not: NUL, blank,
// tabs, line breaks, single-quotes, double-quotes, or backslashes.
int length = 0;
while (Constant.NULL_BL_T_LINEBR.hasNo(reader.peek(length), "\'\"\\")) {
length++;
}
if (length != 0) {
chunks.append(reader.prefixForward(length));
}
// Depending on our quoting-type, the characters ', " and \ have
// differing meanings.
char ch = reader.peek();
if (!doubleQuoted && ch == '\'' && reader.peek(1) == '\'') {
chunks.append("'");
reader.forward(2);
} else if ((doubleQuoted && ch == '\'') || (!doubleQuoted && "\"\\".indexOf(ch) != -1)) {
chunks.append(ch);
reader.forward();
} else if (doubleQuoted && ch == '\\') {
reader.forward();
ch = reader.peek();
if (ESCAPE_REPLACEMENTS.containsKey(Character.valueOf(ch))) {
// The character is one of the single-replacement
// types; these are replaced with a literal character
// from the mapping.
chunks.append(ESCAPE_REPLACEMENTS.get(Character.valueOf(ch)));
reader.forward();
} else if (ESCAPE_CODES.containsKey(Character.valueOf(ch))) {
// The character is a multi-digit escape sequence, with
// length defined by the value in the ESCAPE_CODES map.
length = (ESCAPE_CODES.get(Character.valueOf(ch))).intValue();
reader.forward();
String hex = reader.prefix(length);
if (NOT_HEXA.matcher(hex).find()) {
throw new ScannerException("while scanning a double-quoted scalar", startMark, "expected escape sequence of "
+ length + " hexadecimal numbers, but found: " + hex, reader.getMark());
}
int decimal = Integer.parseInt(hex, 16);
String unicode = new String(Character.toChars(decimal));
chunks.append(unicode);
reader.forward(length);
} else if (scanLineBreak().length() != 0) {
chunks.append(scanFlowScalarBreaks(startMark));
} else {
throw new ScannerException("while scanning a double-quoted scalar", startMark, "found unknown escape character " + ch
+ "(" + ((int) ch) + ")", reader.getMark());
}
} else {
return chunks.toString();
}
}
}
private String scanFlowScalarSpaces(final Mark startMark) {
// See the specification for details.
StringBuilder chunks = new StringBuilder();
int length = 0;
// Scan through any number of whitespace (space, tab) characters,
// consuming them.
while (" \t".indexOf(reader.peek(length)) != -1) {
length++;
}
String whitespaces = reader.prefixForward(length);
char ch = reader.peek();
if (ch == '\0') {
// A flow scalar cannot end with an end-of-stream
throw new ScannerException("while scanning a quoted scalar", startMark, "found unexpected end of stream", reader.getMark());
}
// If we encounter a line break, scan it into our assembled string...
String lineBreak = scanLineBreak();
if (lineBreak.length() != 0) {
String breaks = scanFlowScalarBreaks(startMark);
if (!"\n".equals(lineBreak)) {
chunks.append(lineBreak);
} else if (breaks.length() == 0) {
chunks.append(" ");
}
chunks.append(breaks);
} else {
chunks.append(whitespaces);
}
return chunks.toString();
}
private String scanFlowScalarBreaks(final Mark startMark) {
// See the specification for details.
StringBuilder chunks = new StringBuilder();
while (true) {
// Instead of checking indentation, we check for document
// separators.
String prefix = reader.prefix(3);
if (("---".equals(prefix) || "...".equals(prefix)) && Constant.NULL_BL_T_LINEBR.has(reader.peek(3))) {
throw new ScannerException("while scanning a quoted scalar", startMark, "found unexpected document separator",
reader.getMark());
}
// Scan past any number of spaces and tabs, ignoring them
while (" \t".indexOf(reader.peek()) != -1) {
reader.forward();
}
// If we stopped at a line break, add that; otherwise, return the
// assembled set of scalar breaks.
String lineBreak = scanLineBreak();
if (lineBreak.length() != 0) {
chunks.append(lineBreak);
} else {
return chunks.toString();
}
}
}
/**
* Scan a plain scalar.
*
* <pre>
* See the specification for details.
* We add an additional restriction for the flow context:
* plain scalars in the flow context cannot contain ',', ':' and '?'.
* We also keep track of the `allow_simple_key` flag here.
* Indentation rules are loosed for the flow context.
* </pre>
*/
private Token scanPlain() {
StringBuilder chunks = new StringBuilder();
Mark startMark = reader.getMark();
Mark endMark = startMark;
int indent = this.indent + 1;
String spaces = "";
while (true) {
char ch;
int length = 0;
// A comment indicates the end of the scalar.
if (reader.peek() == '#') {
break;
}
while (true) {
ch = reader.peek(length);
if (Constant.NULL_BL_T_LINEBR.has(ch)
|| (this.flowLevel == 0 && ch == ':' && Constant.NULL_BL_T_LINEBR.has(reader.peek(length + 1)))
|| (this.flowLevel != 0 && ",:?[]{}".indexOf(ch) != -1)) {
break;
}
length++;
}
// It's not clear what we should do with ':' in the flow context.
if (this.flowLevel != 0 && ch == ':' && Constant.NULL_BL_T_LINEBR.hasNo(reader.peek(length + 1), ",[]{}")) {
reader.forward(length);
throw new ScannerException("while scanning a plain scalar", startMark, "found unexpected ':'", reader.getMark(),
"Please check http://pyyaml.org/wiki/YAMLColonInFlowContext for details.");
}
if (length == 0) {
break;
}
this.allowSimpleKey = false;
chunks.append(spaces);
chunks.append(reader.prefixForward(length));
endMark = reader.getMark();
spaces = scanPlainSpaces();
// System.out.printf("spaces[%s]\n", spaces);
if (spaces.length() == 0 || reader.peek() == '#' || (this.flowLevel == 0 && this.reader.getColumn() < indent)) {
break;
}
}
return new ScalarToken(chunks.toString(), startMark, endMark, true);
}
/**
* See the specification for details. SnakeYAML and libyaml allow tabs inside plain scalar
*/
private String scanPlainSpaces() {
int length = 0;
while (reader.peek(length) == ' ' || reader.peek(length) == '\t') {
length++;
}
String whitespaces = reader.prefixForward(length);
String lineBreak = scanLineBreak();
if (lineBreak.length() != 0) {
this.allowSimpleKey = true;
String prefix = reader.prefix(3);
if ("---".equals(prefix) || "...".equals(prefix) && Constant.NULL_BL_T_LINEBR.has(reader.peek(3))) {
return "";
}
StringBuilder breaks = new StringBuilder();
while (true) {
if (reader.peek() == ' ') {
reader.forward();
} else {
String lb = scanLineBreak();
if (lb.length() != 0) {
breaks.append(lb);
prefix = reader.prefix(3);
if ("---".equals(prefix) || "...".equals(prefix) && Constant.NULL_BL_T_LINEBR.has(reader.peek(3))) {
return "";
}
} else {
break;
}
}
}
if (!"\n".equals(lineBreak)) {
return lineBreak + breaks;
} else if (breaks.length() == 0) {
return " ";
}
return breaks.toString();
}
return whitespaces;
}
/**
* <p>
* Scan a Tag handle. A Tag handle takes one of three forms:
*
* <pre>
* "!" (c-primary-tag-handle)
* "!!" (ns-secondary-tag-handle)
* "!(name)!" (c-named-tag-handle)
* </pre>
*
* Where (name) must be formatted as an ns-word-char.
* </p>
*
* @see http://www.yaml.org/spec/1.1/#c-tag-handle
* @see http://www.yaml.org/spec/1.1/#ns-word-char
*
* <pre>
* See the specification for details.
* For some strange reasons, the specification does not allow '_' in
* tag handles. I have allowed it anyway.
* </pre>
*/
private String scanTagHandle(final String name, final Mark startMark) {
char ch = reader.peek();
if (ch != '!') {
throw new ScannerException("while scanning a " + name, startMark, "expected '!', but found " + ch + "(" + ((int) ch) + ")",
reader.getMark());
}
// Look for the next '!' in the stream, stopping if we hit a
// non-word-character. If the first character is a space, then the
// tag-handle is a c-primary-tag-handle ('!').
int length = 1;
ch = reader.peek(length);
if (ch != ' ') {
// Scan through 0+ alphabetic characters.
// FIXME According to the specification, these should be
// ns-word-char only, which prohibits '_'. This might be a
// candidate for a configuration option.
while (Constant.ALPHA.has(ch)) {
length++;
ch = reader.peek(length);
}
// Found the next non-word-char. If this is not a space and not an
// '!', then this is an error, as the tag-handle was specified as:
// !(name) or similar; the trailing '!' is missing.
if (ch != '!') {
reader.forward(length);
throw new ScannerException("while scanning a " + name, startMark, "expected '!', but found " + ch + "(" + ((int) ch) + ")",
reader.getMark());
}
length++;
}
String value = reader.prefixForward(length);
return value;
}
/**
* <p>
* Scan a Tag URI. This scanning is valid for both local and global tag directives, because both appear to be valid URIs as far as
* scanning is concerned. The difference may be distinguished later, in parsing. This method will scan for ns-uri-char*, which covers
* both cases.
* </p>
*
* <p>
* This method performs no verification that the scanned URI conforms to any particular kind of URI specification.
* </p>
*
* @see http://www.yaml.org/spec/1.1/#ns-uri-char
*/
private String scanTagUri(final String name, final Mark startMark) {
// See the specification for details.
// Note: we do not check if URI is well-formed.
StringBuilder chunks = new StringBuilder();
// Scan through accepted URI characters, which includes the standard
// URI characters, plus the start-escape character ('%'). When we get
// to a start-escape, scan the escaped sequence, then return.
int length = 0;
char ch = reader.peek(length);
while (Constant.URI_CHARS.has(ch)) {
if (ch == '%') {
chunks.append(reader.prefixForward(length));
length = 0;
chunks.append(scanUriEscapes(name, startMark));
} else {
length++;
}
ch = reader.peek(length);
}
// Consume the last "chunk", which would not otherwise be consumed by
// the loop above.
if (length != 0) {
chunks.append(reader.prefixForward(length));
length = 0;
}
if (chunks.length() == 0) {
// If no URI was found, an error has occurred.
throw new ScannerException("while scanning a " + name, startMark, "expected URI, but found " + ch + "(" + ((int) ch) + ")",
reader.getMark());
}
return chunks.toString();
}
/**
* <p>
* Scan a sequence of %-escaped URI escape codes and convert them into a String representing the unescaped values.
* </p>
*
* FIXME This method fails for more than 256 bytes' worth of URI-encoded characters in a row. Is this possible? Is this a use-case?
*
* @see http://www.ietf.org/rfc/rfc2396.txt, section 2.4, Escaped Encoding.
*/
private String scanUriEscapes(final String name, final Mark startMark) {
// First, look ahead to see how many URI-escaped characters we should
// expect, so we can use the correct buffer size.
int length = 1;
while (reader.peek(length * 3) == '%') {
length++;
}
// See the specification for details.
// URIs containing 16 and 32 bit Unicode characters are
// encoded in UTF-8, and then each octet is written as a
// separate character.
Mark beginningMark = reader.getMark();
ByteBuffer buff = ByteBuffer.allocate(length);
while (reader.peek() == '%') {
reader.forward();
try {
byte code = (byte) Integer.parseInt(reader.prefix(2), 16);
buff.put(code);
} catch (NumberFormatException nfe) {
throw new ScannerException("while scanning a " + name, startMark,
"expected URI escape sequence of 2 hexadecimal numbers, but found " + reader.peek() + "(" + ((int) reader.peek())
+ ") and " + reader.peek(1) + "(" + ((int) reader.peek(1)) + ")", reader.getMark());
}
reader.forward(2);
}
buff.flip();
try {
return UriEncoder.decode(buff);
} catch (CharacterCodingException e) {
throw new ScannerException("while scanning a " + name, startMark, "expected URI in UTF-8: " + e.getMessage(), beginningMark);
}
}
/**
* Scan a line break, transforming:
*
* <pre>
* '\r\n' : '\n'
* '\r' : '\n'
* '\n' : '\n'
* '\x85' : '\n'
* default : ''
* </pre>
*/
private String scanLineBreak() {
// Transforms:
// '\r\n' : '\n'
// '\r' : '\n'
// '\n' : '\n'
// '\x85' : '\n'
// default : ''
char ch = reader.peek();
if (ch == '\r' || ch == '\n' || ch == '\u0085') {
if (ch == '\r' && '\n' == reader.peek(1)) {
reader.forward(2);
} else {
reader.forward();
}
return "\n";
} else if (ch == '\u2028' || ch == '\u2029') {
reader.forward();
return String.valueOf(ch);
}
return "";
}
/**
* Chomping the tail may have 3 values - yes, no, not defined.
*/
private static class Chomping {
private final Boolean value;
private final int increment;
public Chomping(final Boolean value, final int increment) {
this.value = value;
this.increment = increment;
}
public boolean chompTailIsNotFalse() {
return value == null || value;
}
public boolean chompTailIsTrue() {
return value != null && value;
}
public int getIncrement() {
return increment;
}
}
}