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* ------------------------------------------------------------------------- *
* 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 *
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* Unless required by applicable law or agreed to in writing, software *
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*****************************************************************************/
package net.ion.rosetta;
import net.ion.rosetta.pattern.CharPredicate;
import net.ion.rosetta.pattern.CharPredicates;
import net.ion.rosetta.pattern.Pattern;
import net.ion.rosetta.pattern.Patterns;
/**
* Provides common {@link Parser} implementations that scan the source and match certain string patterns.
* <p>
* Some scanners like {@link #IDENTIFIER} and {@link #INTEGER} return the matched string, while others like {@link #WHITESPACES} return nothing, as indicated by the {@link Void} type parameter. In case the matched string is still needed nontheless, use the {@link Parser#source()} method.
*
* @author Ben Yu
*/
public final class Scanners {
/** A scanner that scans greedily for 1 or more whitespace characters. */
public static final Parser<Void> WHITESPACES = pattern(Patterns.many1(CharPredicates.IS_WHITESPACE), "whitespaces");
/**
* Matches any character in the input. Different from {@link Parsers#always()}, it fails on EOF. Also it consumes the current character in the input.
*/
public static final Parser<Void> ANY_CHAR = new AnyCharScanner("any character");
/** Scanner for c++/java style line comment. */
public static final Parser<Void> JAVA_LINE_COMMENT = lineComment("//");
/** Scanner for SQL style line comment. */
public static final Parser<Void> SQL_LINE_COMMENT = lineComment("--");
/** Scanner for haskell style line comment. ({@code --}) */
public static final Parser<Void> HASKELL_LINE_COMMENT = lineComment("--");
private static final Parser<Void> JAVA_BLOCK_COMMENTED = pattern(notChar2('*', '/').many(), "commented block");
/** Scanner for c++/java style block comment. */
public static final Parser<Void> JAVA_BLOCK_COMMENT = Parsers.sequence(string("/*"), JAVA_BLOCK_COMMENTED, string("*/"));
/** Scanner for SQL style block comment. */
public static final Parser<Void> SQL_BLOCK_COMMENT = Parsers.sequence(string("/*"), JAVA_BLOCK_COMMENTED, string("*/"));
/** Scanner for haskell style block comment. {- -} */
public static final Parser<Void> HASKELL_BLOCK_COMMENT = Parsers.sequence(string("{-"), pattern(notChar2('-', '}').many(), "commented block"), string("-}"));
/**
* Scanner with a pattern for SQL style string literal. A SQL string literal is a string quoted by single quote, a single quote character is escaped by 2 single quotes.
*/
public static final Parser<String> SINGLE_QUOTE_STRING = quotedBy(pattern(Patterns.regex("(('')|[^'])*"), "quoted string"), isChar('\'')).source();
/**
* Scanner with a pattern for double quoted string literal. Backslash '\' is used as escape character.
*/
public static final Parser<String> DOUBLE_QUOTE_STRING = quotedBy(pattern(Patterns.regex("((\\\\.)|[^\"\\\\])*"), "quoted string"), Scanners.isChar('"')).source();
/** Scanner for a c/c++/java style character literal. such as 'a' or '\\'. */
public static final Parser<String> SINGLE_QUOTE_CHAR = quotedBy(pattern(Patterns.regex("(\\\\.)|[^'\\\\]"), "quoted char"), Scanners.isChar('\'')).source();
/**
* Scanner for the c++/java style delimiter of tokens. For example, whitespaces, line comment and block comment.
*/
public static final Parser<Void> JAVA_DELIMITER = Parsers.plus(WHITESPACES, JAVA_LINE_COMMENT, JAVA_BLOCK_COMMENT).skipMany();
/**
* Scanner for the haskell style delimiter of tokens. For example, whitespaces, line comment and block comment.
*/
public static final Parser<Void> HASKELL_DELIMITER = Parsers.plus(WHITESPACES, HASKELL_LINE_COMMENT, HASKELL_BLOCK_COMMENT).skipMany();
/**
* Scanner for the SQL style delimiter of tokens. For example, whitespaces and line comment.
*/
public static final Parser<Void> SQL_DELIMITER = Parsers.plus(WHITESPACES, SQL_LINE_COMMENT, SQL_BLOCK_COMMENT).skipMany();
/**
* Scanner for a regular identifier, that starts with either an underscore or an alpha character, followed by 0 or more alphanumeric characters.
*/
public static final Parser<String> IDENTIFIER = pattern(Patterns.WORD, "word").source();
public static final Parser<String> ARRAY_IDENTIFIER = pattern(Patterns.ARRAYWORD, "array word").source();
/** Scanner for an integer. */
public static final Parser<String> INTEGER = pattern(Patterns.INTEGER, "integer").source();
/** Scanner for a decimal number. */
public static final Parser<String> DECIMAL = pattern(Patterns.DECIMAL, "decimal").source();
/** Scanner for a decimal number. 0 is not allowed as the leading digit. */
public static final Parser<String> DEC_INTEGER = pattern(Patterns.DEC_INTEGER, "decimal integer").source();
/** Scanner for a octal number. 0 is the leading digit. */
public static final Parser<String> OCT_INTEGER = pattern(Patterns.OCT_INTEGER, "octal integer").source();
/**
* Scanner for a hexadecimal number. Has to start with {@code 0x} or {@code 0X}.
*/
public static final Parser<String> HEX_INTEGER = pattern(Patterns.HEX_INTEGER, "hexadecimal integer").source();
/** Scanner for a scientific notation. */
public static final Parser<String> SCIENTIFIC_NOTATION = pattern(Patterns.SCIENTIFIC_NOTATION, "scientific notation").source();
/**
* A scanner that scans greedily for 0 or more characters that satisfies the given CharPredicate.
*
* @param predicate
* the predicate object.
* @return the Parser object.
*/
public static Parser<Void> many(CharPredicate predicate) {
return pattern(Patterns.isChar(predicate).many(), predicate + "*");
}
/**
* A scanner that scans greedily for 1 or more characters that satisfies the given CharPredicate.
*
* @param predicate
* the predicate object.
* @return the Parser object.
*/
public static Parser<Void> many1(CharPredicate predicate) {
return pattern(Patterns.many1(predicate), predicate + "+");
}
/**
* A scanner that scans greedily for 0 or more occurrences of the given pattern.
*
* @param pattern
* the pattern object.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the Parser object.
*/
public static Parser<Void> many(Pattern pattern, String name) {
return pattern(pattern.many(), name);
}
/**
* A scanner that scans greedily for 1 or more occurrences of the given pattern.
*
* @param pattern
* the pattern object.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the Parser object.
*/
public static Parser<Void> many1(Pattern pattern, String name) {
return pattern(pattern.many1(), name);
}
/**
* Matches the input against the specified string.
*
* @param str
* the string to match
* @return the scanner.
*/
public static Parser<Void> string(String str) {
return string(str, str);
}
/**
* Matches the input against the specified string.
*
* @param str
* the string to match
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> string(String str, String name) {
return pattern(Patterns.string(str), name);
}
/**
* A scanner that scans the input for an occurrence of a string pattern.
*
* @param pattern
* the pattern object.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the Parser object.
*/
public static Parser<Void> pattern(Pattern pattern, String name) {
return new PatternScanner(name, pattern);
}
/**
* A scanner that matches the input against the specified string case insensitively.
*
* @param str
* the string to match
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> stringCaseInsensitive(String str, String name) {
return pattern(Patterns.stringCaseInsensitive(str), name);
}
/**
* A scanner that matches the input against the specified string case insensitively.
*
* @param str
* the string to match
* @return the scanner.
*/
public static Parser<Void> stringCaseInsensitive(String str) {
return stringCaseInsensitive(str, str);
}
/**
* A scanner that succeeds and consumes the current character if it satisfies the given {@link CharPredicate}.
*
* @param predicate
* the predicate.
* @return the scanner.
*/
public static Parser<Void> isChar(CharPredicate predicate) {
return isChar(predicate, predicate.toString());
}
/**
* A scanner that succeeds and consumes the current character if it satisfies the given {@link CharPredicate}.
*
* @param predicate
* the predicate.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> isChar(CharPredicate predicate, String name) {
return new IsCharScanner(name, predicate);
}
/**
* A scanner that succeeds and consumes the current character if it is equal to {@code ch}.
*
* @param ch
* the expected character.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> isChar(char ch, String name) {
return isChar(CharPredicates.isChar(ch), name);
}
/**
* A scanner that succeeds and consumes the current character if it is equal to {@code ch}.
*
* @param ch
* the expected character.
* @return the scanner.
*/
public static Parser<Void> isChar(char ch) {
return isChar(ch, Character.toString(ch));
}
/**
* A scanner that succeeds and consumes the current character if it is equal to {@code ch}.
*
* @param ch
* the expected character.
* @param name
* the name of what's expected logically. Is used in error mesage.
* @return the scanner.
*/
public static Parser<Void> notChar(char ch, String name) {
return isChar(CharPredicates.notChar(ch), name);
}
/**
* A scanner that succeeds and consumes the current character if it is not equal to {@code ch}.
*
* @param ch
* the expected character.
* @return the scanner.
*/
public static Parser<Void> notChar(char ch) {
return notChar(ch, "^" + ch);
}
/**
* A scanner that succeeds and consumes the current character if it equals to any character in {@code chars}.
*
* @param chars
* the characters.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> among(String chars, String name) {
return isChar(CharPredicates.among(chars), name);
}
/**
* A scanner that succeeds and consumes the current character if it equals to any character in {@code chars}.
*/
public static Parser<Void> among(String chars) {
if (chars.length() == 0)
return isChar(CharPredicates.NEVER);
if (chars.length() == 1)
return isChar(chars.charAt(0));
return isChar(CharPredicates.among(chars));
}
/**
* A scanner that succeeds and consumes the current character if it is not equal to any character in {@code chars}.
*
* @param chars
* the characters.
* @param name
* the name of what's expected logically. Is used in error message.
* @return the scanner.
*/
public static Parser<Void> notAmong(String chars, String name) {
return isChar(CharPredicates.notAmong(chars), name);
}
/**
* A scanner that succeeds and consumes the current character if it is not equal to any character in {@code chars}.
*/
public static Parser<Void> notAmong(String chars) {
if (chars.length() == 0)
return ANY_CHAR;
if (chars.length() == 1)
return notChar(chars.charAt(0));
return isChar(CharPredicates.notAmong(chars));
}
/**
* A scanner that succeeds and consumes all the characters until the {@code '\n'} character if the current input starts with the string literal {@code begin}. The {@code '\n'} character isn't consumed.
*/
public static Parser<Void> lineComment(String begin) {
return pattern(Patterns.lineComment(begin), begin);
}
/**
* A scanner for non-nested block comment that starts with {@code begin} and ends with {@code end}.
*/
public static Parser<Void> blockComment(String begin, String end) {
Pattern opening = Patterns.string(begin).next(Patterns.notString(end).many());
return pattern(opening, begin).next(string(end));
}
/**
* A scanner for a non-nestable block comment that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* begins a block comment
* @param end
* ends a block comment
* @param commented
* the commented pattern.
* @return the Scanner for the block comment.
*/
public static Parser<Void> blockComment(String begin, String end, Pattern commented) {
Pattern opening = Patterns.string(begin).next(Patterns.string(end).not().next(commented).many());
return pattern(opening, begin).next(string(end));
}
/**
* A scanner for a non-nestable block comment that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* begins a block comment
* @param end
* ends a block comment
* @param commented
* the commented pattern.
* @return the Scanner for the block comment.
*/
public static Parser<Void> blockComment(Parser<Void> begin, Parser<Void> end, Parser<?> commented) {
return Parsers.sequence(begin, end.not().next(commented).skipMany(), end);
}
/**
* A scanner for a nestable block comment that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* begins a block comment
* @param end
* ends a block comment
* @return the block comment scanner.
*/
public static Parser<Void> nestableBlockComment(String begin, String end) {
return nestableBlockComment(begin, end, Patterns.isChar(CharPredicates.ALWAYS));
}
/**
* A scanner for a nestable block comment that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* begins a block comment
* @param end
* ends a block comment
* @param commented
* the commented pattern except for nested comments.
* @return the block comment scanner.
*/
public static Parser<Void> nestableBlockComment(String begin, String end, Pattern commented) {
return nestableBlockComment(string(begin), string(end), pattern(commented, "commented"));
}
/**
* A scanner for a nestable block comment that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* starts a block comment
* @param end
* ends a block comment
* @param commented
* the commented pattern except for nested comments.
* @return the block comment scanner.
*/
public static Parser<Void> nestableBlockComment(Parser<?> begin, Parser<?> end, Parser<?> commented) {
return new NestableBlockCommentScanner(begin, end, commented);
}
/**
* A scanner for a quoted string that starts with character {@code begin} and ends with character {@code end}.
*/
public static Parser<String> quoted(char begin, char end) {
Pattern beforeClosingQuote = Patterns.isChar(begin).next(Patterns.many(CharPredicates.notChar(end)));
return pattern(beforeClosingQuote, Character.toString(begin)).next(isChar(end)).source();
}
/**
* A scanner for a quoted string that starts with {@code begin} and ends with {@code end}.
*
* @param begin
* begins a quote
* @param end
* ends a quote
* @param quoted
* the parser that recognizes the quoted pattern.
* @return the scanner.
*/
public static Parser<String> quoted(Parser<Void> begin, Parser<Void> end, Parser<?> quoted) {
return Parsers.sequence(begin, quoted.skipMany(), end).source();
}
/**
* A scanner that after character level {@code outer} succeeds, subsequently feeds the recognized characters to {@code inner} for a nested scanning.
*
* <p>
* Is useful for scenaios like parsing string interpolation grammar.
*/
public static Parser<Void> nestedScanner(Parser<?> outer, Parser<Void> inner) {
return new NestedScanner(outer, inner);
}
/**
* Matches a character if the input has at least 1 character, or if the input has at least 2 characters with the first 2 characters not being {@code c1} and {@code c2}.
*
* @return the Pattern object.
*/
private static Pattern notChar2(final char c1, final char c2) {
return new Pattern() {
@Override
public int match(CharSequence src, int begin, int end) {
if (begin == end - 1)
return 1;
if (begin >= end)
return MISMATCH;
if (src.charAt(begin) == c1 && src.charAt(begin + 1) == c2)
return Pattern.MISMATCH;
return 1;
}
};
}
private static Parser<Void> quotedBy(Parser<Void> parser, Parser<?> quote) {
return parser.between(quote, quote);
}
private Scanners() {
}
}