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With inspiration from other libraries
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 2006-2009, Google, International Business Machines Corporation *
* and others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.impl;
import com.ibm.icu.text.UTF16;
import com.ibm.icu.text.UnicodeSet;
/**
* A simple parsing class for patterns and rules. Handles '...' quotations, \\uxxxx and \\Uxxxxxxxx, and symple syntax.
* The '' (two quotes) is treated as a single quote, inside or outside a quote
*
* - Any ignorable characters are ignored in parsing.
* - Any syntax characters are broken into separate tokens
* - Quote characters can be specified: '...', "...", and \x
* - Other characters are treated as literals
*
*/
public class PatternTokenizer {
// settings used in the interpretation of the pattern
private UnicodeSet ignorableCharacters = new UnicodeSet();
private UnicodeSet syntaxCharacters = new UnicodeSet();
private UnicodeSet extraQuotingCharacters = new UnicodeSet();
private UnicodeSet escapeCharacters = new UnicodeSet();
private boolean usingSlash = false;
private boolean usingQuote = false;
// transient data, set when needed. Null it out for any changes in the above fields.
private transient UnicodeSet needingQuoteCharacters = null;
// data about the current pattern being parsed. start gets moved as we go along.
private int start;
private int limit;
private String pattern;
public UnicodeSet getIgnorableCharacters() {
return (UnicodeSet) ignorableCharacters.clone();
}
/**
* Sets the characters to be ignored in parsing, eg new UnicodeSet("[:pattern_whitespace:]");
* @param ignorableCharacters Characters to be ignored.
* @return A PatternTokenizer object in which characters are specified as ignored characters.
*/
public PatternTokenizer setIgnorableCharacters(UnicodeSet ignorableCharacters) {
this.ignorableCharacters = (UnicodeSet) ignorableCharacters.clone();
needingQuoteCharacters = null;
return this;
}
public UnicodeSet getSyntaxCharacters() {
return (UnicodeSet) syntaxCharacters.clone();
}
public UnicodeSet getExtraQuotingCharacters() {
return (UnicodeSet) extraQuotingCharacters.clone();
}
/**
* Sets the characters to be interpreted as syntax characters in parsing, eg new UnicodeSet("[:pattern_syntax:]")
* @param syntaxCharacters Characters to be set as syntax characters.
* @return A PatternTokenizer object in which characters are specified as syntax characters.
*/
public PatternTokenizer setSyntaxCharacters(UnicodeSet syntaxCharacters) {
this.syntaxCharacters = (UnicodeSet) syntaxCharacters.clone();
needingQuoteCharacters = null;
return this;
}
/**
* Sets the extra characters to be quoted in literals
* @param syntaxCharacters Characters to be set as extra quoting characters.
* @return A PatternTokenizer object in which characters are specified as extra quoting characters.
*/
public PatternTokenizer setExtraQuotingCharacters(UnicodeSet syntaxCharacters) {
this.extraQuotingCharacters = (UnicodeSet) syntaxCharacters.clone();
needingQuoteCharacters = null;
return this;
}
public UnicodeSet getEscapeCharacters() {
return (UnicodeSet) escapeCharacters.clone();
}
/**
* Set characters to be escaped in literals, in quoteLiteral and normalize, eg new UnicodeSet("[^\\u0020-\\u007E]");
* @param escapeCharacters Characters to be set as escape characters.
* @return A PatternTokenizer object in which characters are specified as escape characters.
*/
public PatternTokenizer setEscapeCharacters(UnicodeSet escapeCharacters) {
this.escapeCharacters = (UnicodeSet) escapeCharacters.clone();
return this;
}
public boolean isUsingQuote() {
return usingQuote;
}
public PatternTokenizer setUsingQuote(boolean usingQuote) {
this.usingQuote = usingQuote;
needingQuoteCharacters = null;
return this;
}
public boolean isUsingSlash() {
return usingSlash;
}
public PatternTokenizer setUsingSlash(boolean usingSlash) {
this.usingSlash = usingSlash;
needingQuoteCharacters = null;
return this;
}
// public UnicodeSet getQuoteCharacters() {
// return (UnicodeSet) quoteCharacters.clone();
// }
// public PatternTokenizer setQuoteCharacters(UnicodeSet quoteCharacters) {
// this.quoteCharacters = (UnicodeSet) quoteCharacters.clone();
// needingQuoteCharacters = null;
// return this;
// }
public int getLimit() {
return limit;
}
public PatternTokenizer setLimit(int limit) {
this.limit = limit;
return this;
}
public int getStart() {
return start;
}
public PatternTokenizer setStart(int start) {
this.start = start;
return this;
}
public PatternTokenizer setPattern(CharSequence pattern) {
return setPattern(pattern.toString());
}
public PatternTokenizer setPattern(String pattern) {
if (pattern == null) {
throw new IllegalArgumentException("Inconsistent arguments");
}
this.start = 0;
this.limit = pattern.length();
this.pattern = pattern;
return this;
}
public static final char SINGLE_QUOTE = '\'';
public static final char BACK_SLASH = '\\';
private static int NO_QUOTE = -1, IN_QUOTE = -2;
public String quoteLiteral(CharSequence string) {
return quoteLiteral(string.toString());
}
/**
* Quote a literal string, using the available settings. Thus syntax characters, quote characters, and ignorable characters will be put into quotes.
* @param string String passed to quote a literal string.
* @return A string using the available settings will place syntax, quote, or ignorable characters into quotes.
*/
public String quoteLiteral(String string) {
if (needingQuoteCharacters == null) {
needingQuoteCharacters = new UnicodeSet().addAll(syntaxCharacters).addAll(ignorableCharacters).addAll(extraQuotingCharacters); // .addAll(quoteCharacters)
if (usingSlash) needingQuoteCharacters.add(BACK_SLASH);
if (usingQuote) needingQuoteCharacters.add(SINGLE_QUOTE);
}
StringBuffer result = new StringBuffer();
int quotedChar = NO_QUOTE;
int cp;
for (int i = 0; i < string.length(); i += UTF16.getCharCount(cp)) {
cp = UTF16.charAt(string, i);
if (escapeCharacters.contains(cp)) {
// we may have to fix up previous characters
if (quotedChar == IN_QUOTE) {
result.append(SINGLE_QUOTE);
quotedChar = NO_QUOTE;
}
appendEscaped(result, cp);
continue;
}
if (needingQuoteCharacters.contains(cp)) {
// if we have already started a quote
if (quotedChar == IN_QUOTE) {
UTF16.append(result, cp);
if (usingQuote && cp == SINGLE_QUOTE) { // double it
result.append(SINGLE_QUOTE);
}
continue;
}
// otherwise not already in quote
if (usingSlash) {
result.append(BACK_SLASH);
UTF16.append(result, cp);
continue;
}
if (usingQuote) {
if (cp == SINGLE_QUOTE) { // double it and continue
result.append(SINGLE_QUOTE);
result.append(SINGLE_QUOTE);
continue;
}
result.append(SINGLE_QUOTE);
UTF16.append(result, cp);
quotedChar = IN_QUOTE;
continue;
}
// we have no choice but to use \\u or \\U
appendEscaped(result, cp);
continue;
}
// otherwise cp doesn't need quoting
// we may have to fix up previous characters
if (quotedChar == IN_QUOTE) {
result.append(SINGLE_QUOTE);
quotedChar = NO_QUOTE;
}
UTF16.append(result, cp);
}
// all done.
// we may have to fix up previous characters
if (quotedChar == IN_QUOTE) {
result.append(SINGLE_QUOTE);
}
return result.toString();
}
private void appendEscaped(StringBuffer result, int cp) {
if (cp <= 0xFFFF) {
result.append("\\u").append(Utility.hex(cp,4));
} else {
result.append("\\U").append(Utility.hex(cp,8));
}
}
public String normalize() {
int oldStart = start;
StringBuffer result = new StringBuffer();
StringBuffer buffer = new StringBuffer();
while (true) {
buffer.setLength(0);
int status = next(buffer);
if (status == DONE) {
start = oldStart;
return result.toString();
}
if (status != SYNTAX) {
result.append(quoteLiteral(buffer));
} else {
result.append(buffer);
}
}
}
public static final int DONE = 0, SYNTAX = 1, LITERAL = 2, BROKEN_QUOTE = 3, BROKEN_ESCAPE = 4, UNKNOWN = 5;
private static final int AFTER_QUOTE = -1, NONE = 0, START_QUOTE = 1, NORMAL_QUOTE = 2, SLASH_START = 3, HEX = 4;
public int next(StringBuffer buffer) {
if (start >= limit) return DONE;
int status = UNKNOWN;
int lastQuote = UNKNOWN;
int quoteStatus = NONE;
int hexCount = 0;
int hexValue = 0;
int cp;
main:
for (int i = start; i < limit; i += UTF16.getCharCount(cp)) {
cp = UTF16.charAt(pattern, i);
// if we are in a quote, then handle it.
switch (quoteStatus) {
case SLASH_START:
switch (cp) {
case 'u':
quoteStatus = HEX;
hexCount = 4;
hexValue = 0;
continue main;
case 'U':
quoteStatus = HEX;
hexCount = 8;
hexValue = 0;
continue main;
default:
if (usingSlash) {
UTF16.append(buffer, cp);
quoteStatus = NONE;
continue main;
} else {
buffer.append(BACK_SLASH);
quoteStatus = NONE;
}
}
break; // fall through to NONE
case HEX:
hexValue <<= 4;
hexValue += cp;
switch (cp) {
case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9':
hexValue -= '0'; break;
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
hexValue -= 'a' - 10; break;
case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
hexValue -= 'A' - 10; break;
default:
start = i;
return BROKEN_ESCAPE;
}
--hexCount;
if (hexCount == 0) {
quoteStatus = NONE;
UTF16.append(buffer, hexValue);
}
continue main;
case AFTER_QUOTE:
// see if we get another quote character
// if we just ended a quote BUT the following character is the lastQuote character, then we have a situation like '...''...', so we restart the quote
if (cp == lastQuote) {
UTF16.append(buffer, cp);
quoteStatus = NORMAL_QUOTE;
continue main;
}
quoteStatus = NONE;
break; // fall through to NONE
case START_QUOTE:
// if we are at the very start of a quote, and we hit another quote mark then we emit a literal quote character and end the quote
if (cp == lastQuote) {
UTF16.append(buffer, cp);
quoteStatus = NONE; // get out of quote, with no trace remaining
continue;
}
// otherwise get into quote
UTF16.append(buffer, cp);
quoteStatus = NORMAL_QUOTE;
continue main;
case NORMAL_QUOTE:
if (cp == lastQuote) {
quoteStatus = AFTER_QUOTE; // get out of quote
continue main;
}
UTF16.append(buffer, cp);
continue main;
}
if (ignorableCharacters.contains(cp)) {
continue;
}
// do syntax characters
if (syntaxCharacters.contains(cp)) {
if (status == UNKNOWN) {
UTF16.append(buffer, cp);
start = i + UTF16.getCharCount(cp);
return SYNTAX;
} else { // LITERAL, so back up and break
start = i;
return status;
}
}
// otherwise it is a literal; keep on going
status = LITERAL;
if (cp == BACK_SLASH) {
quoteStatus = SLASH_START;
continue;
} else if (usingQuote && cp == SINGLE_QUOTE) {
lastQuote = cp;
quoteStatus = START_QUOTE;
continue;
}
// normal literals
UTF16.append(buffer, cp);
}
// handle final cleanup
start = limit;
switch (quoteStatus) {
case HEX:
status = BROKEN_ESCAPE;
break;
case SLASH_START:
if (usingSlash) {
status = BROKEN_ESCAPE;
} else {
buffer.append(BACK_SLASH);
}
break;
case START_QUOTE: case NORMAL_QUOTE:
status = BROKEN_QUOTE;
break;
}
return status;
}
}
//eof