/*******************************************************************************
* Copyright (c) 2014, 2015 Cisco Systems, Inc. and others. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 which accompanies this distribution,
* and is available at http://www.eclipse.org/legal/epl-v10.html
*
*******************************************************************************/
package com.cisco.yangide.editor.editors.text;
import java.util.Arrays;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.jface.text.ITypedRegion;
import org.eclipse.jface.text.Region;
import org.eclipse.jface.text.TextUtilities;
import org.eclipse.jface.text.TypedRegion;
import com.cisco.yangide.editor.editors.YangScanner;
import com.cisco.yangide.editor.preferences.YangDocumentSetupParticipant;
/**
* Utility methods for heuristic based YANG manipulations in an incomplete YANG source file.
*
* @author Alexey Kholupko
*/
public final class YangHeuristicScanner implements Symbols {
/**
* Returned by all methods when the requested position could not be found
*/
public static final int NOT_FOUND = -1;
/**
* Special bound parameter that means either -1 (backward scanning) or
* <code>fDocument.getLength()</code> (forward scanning).
*/
public static final int UNBOUND = -2;
/* character constants */
private static final char LBRACE = '{';
private static final char RBRACE = '}';
private static final char LPAREN = '(';
private static final char RPAREN = ')';
private static final char SEMICOLON = ';';
private static final char COLON = ':';
private static final char COMMA = ',';
private static final char LBRACKET = '[';
private static final char RBRACKET = ']';
private static final char QUESTIONMARK = '?';
private static final char EQUAL = '=';
private static final char LANGLE = '<';
private static final char RANGLE = '>';
private static final char PLUS = '+';
private static final char AT = '@';
/**
* Specifies the stop condition, upon which the <code>scanXXX</code> methods will decide whether
* to keep scanning or not. This interface may implemented by clients.
*/
private static abstract class StopCondition {
/**
* Instructs the scanner to return the current position.
*
* @param ch the char at the current position
* @param position the current position
* @param forward the iteration direction
* @return <code>true</code> if the stop condition is met.
*/
public abstract boolean stop(char ch, int position, boolean forward);
/**
* Asks the condition to return the next position to query. The default is to return the
* next/previous position.
*
* @param position the position
* @param forward <code>true</code> if next position should be returned
* @return the next position to scan
*/
public int nextPosition(int position, boolean forward) {
return forward ? position + 1 : position - 1;
}
}
/**
* Stops upon a non-whitespace (as defined by {@link Character#isWhitespace(char)}) character.
*/
private static class NonWhitespace extends StopCondition {
/*
* @see com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#stop(char)
*/
@Override
public boolean stop(char ch, int position, boolean forward) {
return !Character.isWhitespace(ch);
}
}
/**
* Stops upon a non-whitespace character in the default partition.
*
* @see YangHeuristicScanner.NonWhitespace
*/
private final class NonWhitespaceDefaultPartition extends NonWhitespace {
/*
* @see com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#stop(char)
*/
@Override
public boolean stop(char ch, int position, boolean forward) {
return super.stop(ch, position, true) && isDefaultPartition(position);
}
/*
* @see
* com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#nextPosition
* (int, boolean)
*/
@Override
public int nextPosition(int position, boolean forward) {
ITypedRegion partition = getPartition(position);
if (fPartition.equals(partition.getType()))
return super.nextPosition(position, forward);
if (forward) {
int end = partition.getOffset() + partition.getLength();
if (position < end)
return end;
} else {
int offset = partition.getOffset();
if (position > offset)
return offset - 1;
}
return super.nextPosition(position, forward);
}
}
/**
* Stops upon a non-YANG identifier (as defined by {@link #isYAngIdentifierPart(char)})
* character.
*/
private static class NonYangIdentifierPart extends StopCondition {
/*
* @see com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#stop(char)
*/
@Override
public boolean stop(char ch, int position, boolean forward) {
return !isYangIdentifierPart(ch);
}
}
/**
* Stops upon a non-YANG identifier character in the default partition.
*
* @see YangHeuristicScanner.NonYangIdentifierPart
*/
private final class NonYangIdentifierPartDefaultPartition extends NonYangIdentifierPart {
/*
* @see com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#stop(char)
*/
@Override
public boolean stop(char ch, int position, boolean forward) {
return super.stop(ch, position, true) || !isDefaultPartition(position);
}
/*
* @see
* com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#nextPosition
* (int, boolean)
*/
@Override
public int nextPosition(int position, boolean forward) {
ITypedRegion partition = getPartition(position);
if (fPartition.equals(partition.getType()))
return super.nextPosition(position, forward);
if (forward) {
int end = partition.getOffset() + partition.getLength();
if (position < end)
return end;
} else {
int offset = partition.getOffset();
if (position > offset)
return offset - 1;
}
return super.nextPosition(position, forward);
}
}
/**
* Stops upon a character in the default partition that matches the given character list.
*/
private final class CharacterMatch extends StopCondition {
private final char[] fChars;
/**
* Creates a new instance.
*
* @param ch the single character to match
*/
public CharacterMatch(char ch) {
this(new char[] { ch });
}
/**
* Creates a new instance.
*
* @param chars the chars to match.
*/
public CharacterMatch(char[] chars) {
Assert.isNotNull(chars);
Assert.isTrue(chars.length > 0);
fChars = chars;
Arrays.sort(chars);
}
/*
* @see com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#stop(char,
* int)
*/
@Override
public boolean stop(char ch, int position, boolean forward) {
return Arrays.binarySearch(fChars, ch) >= 0 && isDefaultPartition(position);
}
/*
* @see
* com.cisco.yangide.editor.editors.text.YangHeuristicScanner.StopCondition#nextPosition
* (int, boolean)
*/
@Override
public int nextPosition(int position, boolean forward) {
ITypedRegion partition = getPartition(position);
if (fPartition.equals(partition.getType()))
return super.nextPosition(position, forward);
if (forward) {
int end = partition.getOffset() + partition.getLength();
if (position < end)
return end;
} else {
int offset = partition.getOffset();
if (position > offset)
return offset - 1;
}
return super.nextPosition(position, forward);
}
}
/** The document being scanned. */
private final IDocument fDocument;
/** The partitioning being used for scanning. */
private final String fPartitioning;
/** The partition to scan in. */
private final String fPartition;
/* internal scan state */
/** the most recently read character. */
private char fChar;
/** the most recently read position. */
private int fPos;
/**
* The most recently used partition.
*/
private ITypedRegion fCachedPartition = new TypedRegion(-1, 0, "__no_partition_at_all"); //$NON-NLS-1$
/* preset stop conditions */
private final StopCondition fNonWSDefaultPart = new NonWhitespaceDefaultPartition();
private final static StopCondition fNonWS = new NonWhitespace();
private final StopCondition fNonIdent = new NonYangIdentifierPartDefaultPartition();
/**
* Creates a new instance.
*
* @param document the document to scan
* @param partitioning the partitioning to use for scanning
* @param partition the partition to scan in
*/
public YangHeuristicScanner(IDocument document, String partitioning, String partition) {
Assert.isLegal(document != null);
Assert.isLegal(partitioning != null);
Assert.isLegal(partition != null);
fDocument = document;
fPartitioning = partitioning;
fPartition = partition;
}
/**
* Calls
* <code>this(document, YangDocumentSetupParticipant.YANG_PARTITIONING, IDocument.DEFAULT_CONTENT_TYPE)</code>
*
* @param document the document to scan.
*/
public YangHeuristicScanner(IDocument document) {
this(document, YangDocumentSetupParticipant.YANG_PARTITIONING, IDocument.DEFAULT_CONTENT_TYPE);
}
/**
* Returns the most recent internal scan position.
*/
public int getPosition() {
return fPos;
}
/**
* Returns the next token in forward direction, starting at <code>start</code>, and not
* extending further than <code>bound</code>. The return value is one of the constants defined
* in {@link Symbols}. After a call, {@link #getPosition()} will return the position just after
* the scanned token (i.e. the next position that will be scanned).
*/
public int nextToken(int start, int bound) {
int pos = scanForward(start, bound, fNonWSDefaultPart);
if (pos == NOT_FOUND)
return TokenEOF;
fPos++;
switch (fChar) {
case LBRACE:
return TokenLBRACE;
case RBRACE:
return TokenRBRACE;
case LBRACKET:
return TokenLBRACKET;
case RBRACKET:
return TokenRBRACKET;
case LPAREN:
return TokenLPAREN;
case RPAREN:
return TokenRPAREN;
case SEMICOLON:
return TokenSEMICOLON;
case COMMA:
return TokenCOMMA;
case QUESTIONMARK:
return TokenQUESTIONMARK;
case EQUAL:
return TokenEQUAL;
case LANGLE:
return TokenLESSTHAN;
case RANGLE:
return TokenGREATERTHAN;
case PLUS:
return TokenPLUS;
case AT:
return TokenAT;
}
// else
if (isYangIdentifierPart(fChar)) {
// assume an identifier or keyword
int from = pos, to;
pos = scanForward(pos + 1, bound, fNonIdent);
if (pos == NOT_FOUND)
to = bound == UNBOUND ? fDocument.getLength() : bound;
else
to = pos;
String identOrKeyword;
try {
identOrKeyword = fDocument.get(from, to - from);
} catch (BadLocationException e) {
return TokenEOF;
}
return getToken(identOrKeyword);
} else {
// operators, number literals etc
return TokenOTHER;
}
}
/**
* Returns the next token in backward direction, starting at <code>start</code>, and not
* extending further than <code>bound</code>. The return value is one of the constants defined
* in {@link Symbols}. After a call, {@link #getPosition()} will return the position just before
* the scanned token starts (i.e. the next position that will be scanned).
*/
public int previousToken(int start, int bound) {
int pos = scanBackward(start, bound, fNonWSDefaultPart);
if (pos == NOT_FOUND)
return TokenEOF;
fPos--;
switch (fChar) {
case LBRACE:
return TokenLBRACE;
case RBRACE:
return TokenRBRACE;
case LBRACKET:
return TokenLBRACKET;
case RBRACKET:
return TokenRBRACKET;
case LPAREN:
return TokenLPAREN;
case RPAREN:
return TokenRPAREN;
case SEMICOLON:
return TokenSEMICOLON;
case COLON:
return TokenCOLON;
case COMMA:
return TokenCOMMA;
case QUESTIONMARK:
return TokenQUESTIONMARK;
case EQUAL:
return TokenEQUAL;
case LANGLE:
return TokenLESSTHAN;
case RANGLE:
return TokenGREATERTHAN;
case PLUS:
return TokenPLUS;
case AT:
return TokenAT;
}
// else
if (isYangIdentifierPart(fChar)) {
// assume an ident or keyword
int from, to = pos + 1;
pos = scanBackward(pos - 1, bound, fNonIdent);
if (pos == NOT_FOUND)
from = bound == UNBOUND ? 0 : bound + 1;
else
from = pos + 1;
String identOrKeyword;
try {
identOrKeyword = fDocument.get(from, to - from);
} catch (BadLocationException e) {
return TokenEOF;
}
return getToken(identOrKeyword);
} else {
// operators, number literals etc
return TokenOTHER;
}
}
/**
* @param fChar2
* @return
*/
public static boolean isYangIdentifierPart(char fChar2) {
return Character.isJavaIdentifierPart(fChar2) || fChar2 == '-';
}
/**
* Returns one of the keyword constants or <code>TokenIDENT</code> for a scanned identifier.
*
* @param s a scanned identifier
* @return one of the constants defined in {@link Symbols}
*/
private int getToken(String s) {
Assert.isNotNull(s);
// TODO types are separate tokens
if (Arrays.asList(YangScanner.getKeywords()).contains(s) || Arrays.asList(YangScanner.getTypes()).contains(s))
return TokenKEYWORD;
return TokenIDENT;
}
/**
* Returns the position of the closing peer character (forward search). Any scopes introduced by
* opening peers are skipped. All peers accounted for must reside in the default partition.
* <p>
* <code>start</code> must not point to the opening peer, but to the first character being
* searched.
* </p>
*/
public int findClosingPeer(int start, final char openingPeer, final char closingPeer) {
return findClosingPeer(start, UNBOUND, openingPeer, closingPeer);
}
public int findClosingPeer(int start, int bound, final char openingPeer, final char closingPeer) {
Assert.isLegal(start >= 0);
try {
CharacterMatch match = new CharacterMatch(new char[] { openingPeer, closingPeer });
int depth = 1;
start -= 1;
while (true) {
start = scanForward(start + 1, bound, match);
if (start == NOT_FOUND)
return NOT_FOUND;
if (fDocument.getChar(start) == openingPeer)
depth++;
else
depth--;
if (depth == 0)
return start;
}
} catch (BadLocationException e) {
return NOT_FOUND;
}
}
/**
* Returns the position of the opening peer character (backward search). Any scopes introduced
* by closing peers are skipped. All peers accounted for must reside in the default partition.
* <p>
* <code>start</code> must not point to the closing peer, but to the first character being
* searched.
* </p>
*/
public int findOpeningPeer(int start, char openingPeer, char closingPeer) {
return findOpeningPeer(start, UNBOUND, openingPeer, closingPeer);
}
public int findOpeningPeer(int start, int bound, char openingPeer, char closingPeer) {
Assert.isLegal(start < fDocument.getLength());
try {
final CharacterMatch match = new CharacterMatch(new char[] { openingPeer, closingPeer });
int depth = 1;
start += 1;
while (true) {
start = scanBackward(start - 1, bound, match);
if (start == NOT_FOUND)
return NOT_FOUND;
if (fDocument.getChar(start) == closingPeer)
depth++;
else
depth--;
if (depth == 0)
return start;
}
} catch (BadLocationException e) {
return NOT_FOUND;
}
}
/**
* Computes the surrounding block around <code>offset</code>. The search is started at the
* beginning of <code>offset</code>, i.e. an opening brace at <code>offset</code> will not be
* part of the surrounding block, but a closing brace will.
*/
public IRegion findSurroundingBlock(int offset) {
if (offset < 1 || offset >= fDocument.getLength())
return null;
int begin = findOpeningPeer(offset - 1, LBRACE, RBRACE);
int end = findClosingPeer(offset, LBRACE, RBRACE);
if (begin == NOT_FOUND || end == NOT_FOUND)
return null;
return new Region(begin, end + 1 - begin);
}
/**
* Finds the smallest position in <code>fDocument</code> such that the position is >=
* <code>position</code> and < <code>bound</code> and
* <code>Character.isWhitespace(fDocument.getChar(pos))</code> evaluates to <code>false</code>
* and the position is in the default partition.
*/
public int findNonWhitespaceForward(int position, int bound) {
return scanForward(position, bound, fNonWSDefaultPart);
}
public int findNonWhitespaceForwardInAnyPartition(int position, int bound) {
return scanForward(position, bound, fNonWS);
}
/**
* Finds the highest position in <code>fDocument</code> such that the position is <=
* <code>position</code> and > <code>bound</code> and
* <code>Character.isWhitespace(fDocument.getChar(pos))</code> evaluates to <code>false</code>
* and the position is in the default partition.
*/
public int findNonWhitespaceBackward(int position, int bound) {
return scanBackward(position, bound, fNonWSDefaultPart);
}
public int findNonWhitespaceBackwardInAnyPartition(int position, int bound) {
return scanBackward(position, bound, fNonWS);
}
/**
* Finds the lowest position <code>p</code> in <code>fDocument</code> such that
* <code>start</code> <= p < <code>bound</code> and
* <code>condition.stop(fDocument.getChar(p), p)</code> evaluates to <code>true</code>.
*/
public int scanForward(int start, int bound, StopCondition condition) {
Assert.isLegal(start >= 0);
if (bound == UNBOUND)
bound = fDocument.getLength();
Assert.isLegal(bound <= fDocument.getLength());
try {
fPos = start;
while (fPos < bound) {
fChar = fDocument.getChar(fPos);
if (condition.stop(fChar, fPos, true))
return fPos;
fPos = condition.nextPosition(fPos, true);
}
} catch (BadLocationException e) {
}
return NOT_FOUND;
}
public int scanForward(int position, int bound, char ch) {
return scanForward(position, bound, new CharacterMatch(ch));
}
public int scanForward(int position, int bound, char[] chars) {
return scanForward(position, bound, new CharacterMatch(chars));
}
public int scanBackward(int start, int bound, StopCondition condition) {
if (bound == UNBOUND)
bound = -1;
Assert.isLegal(bound >= -1);
Assert.isLegal(start < fDocument.getLength());
try {
fPos = start;
while (fPos > bound) {
fChar = fDocument.getChar(fPos);
if (condition.stop(fChar, fPos, false))
return fPos;
fPos = condition.nextPosition(fPos, false);
}
} catch (BadLocationException e) {
}
return NOT_FOUND;
}
public int scanBackward(int position, int bound, char ch) {
return scanBackward(position, bound, new CharacterMatch(ch));
}
public int scanBackward(int position, int bound, char[] chars) {
return scanBackward(position, bound, new CharacterMatch(chars));
}
/**
* Checks whether <code>position</code> resides in a default (YANG) partition of
* <code>fDocument</code>.
*/
public boolean isDefaultPartition(int position) {
return fPartition.equals(getPartition(position).getType());
}
/**
* Returns the partition at <code>position</code>.
*/
private ITypedRegion getPartition(int position) {
if (!contains(fCachedPartition, position)) {
Assert.isTrue(position >= 0);
Assert.isTrue(position <= fDocument.getLength());
try {
fCachedPartition = TextUtilities.getPartition(fDocument, fPartitioning, position, false);
} catch (BadLocationException e) {
fCachedPartition = new TypedRegion(position, 0, "__no_partition_at_all"); //$NON-NLS-1$
}
}
return fCachedPartition;
}
/**
* Returns <code>true</code> if <code>region</code> contains <code>position</code>.
*/
private boolean contains(IRegion region, int position) {
int offset = region.getOffset();
return offset <= position && position < offset + region.getLength();
}
/**
* Checks if the line seems to be an open condition not followed by a block (i.e. statement with
* just one following statement).
*/
public boolean isBracelessBlockStart(int position, int bound) {
if (position < 1)
return false;
switch (previousToken(position, bound)) {
// for example:
// description
// "This is..."
case TokenKEYWORD:
return true;
}
return false;
}
}