/*
* Svjatoslav Commons - shared library of common functionality.
* Copyright ©2012-2017, Svjatoslav Agejenko, svjatoslav@svjatoslav.eu
- *
+ *
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 3 of the GNU Lesser General Public License
* or later as published by the Free Software Foundation.
public class Tokenizer {
- final Stack<Integer> tokenIndexes = new Stack<>();
+ private final Stack<Integer> tokenIndexes = new Stack<>();
private final List<Terminator> terminators = new ArrayList<>();
private String source;
private int currentIndex = 0;
+ private int cachedTerminatorIndex = -1;
+ private Terminator cachedTerminator;
+
public Tokenizer(final String source) {
this.source = source;
}
- public Tokenizer(){}
+ public Tokenizer() {
+ }
- public Tokenizer setSource(String source){
+ public Tokenizer setSource(String source) {
this.source = source;
currentIndex = 0;
tokenIndexes.clear();
+
+ cachedTerminatorIndex = -1;
+ cachedTerminator = null;
return this;
}
+ "\" but got \"" + match.token + "\" instead.");
}
- public TokenizerMatch getNextToken() {
+
+ public TokenizerMatch getNextToken() throws InvalidSyntaxException {
tokenIndexes.push(currentIndex);
- StringBuilder token = new StringBuilder();
-
- while (true){
- if (isTokenTermination()){
- Terminator tokenTerminator = findTokenTerminator();
-
- if (tokenTerminator.termination == PRESERVE){
- if (hasAccumulatedToken(token)){
- // already assembled some token
- return new TokenizerMatch(token.toString(), "", tokenTerminator);
- } else {
- currentIndex++;
- return new TokenizerMatch(tokenTerminator.startSequence, "", tokenTerminator);
- }
- } else if (tokenTerminator.termination == DROP){
- if (hasAccumulatedToken(token)){
- currentIndex++;
- return new TokenizerMatch(token.toString(), "", tokenTerminator);
- } else {
- currentIndex++;
- }
- }
- } else {
- token.append(source.charAt(currentIndex));
+ StringBuilder tokenAccumulator = new StringBuilder();
+
+ while (true) {
+
+ if (currentIndex >= source.length()) { // reached end of input
+ if (hasAccumulatedToken(tokenAccumulator))
+ return new TokenizerMatch(tokenAccumulator.toString(), null, null);
+ else
+ return null;
+ }
+
+ if (isOngoingToken()) {
+ tokenAccumulator.append(source.charAt(currentIndex));
currentIndex++;
+ continue;
+ }
+
+ Terminator terminator = getOrFindTokenTerminator();
+
+ if (terminator.termination == PRESERVE)
+ return buildPreservedToken(tokenAccumulator, terminator);
+ else if (terminator.termination == DROP) {
+ skipUntilTerminatorEnd(terminator);
+
+ if (hasAccumulatedToken(tokenAccumulator))
+ return new TokenizerMatch(tokenAccumulator.toString(), null, terminator);
}
}
}
+ private void skipUntilTerminatorEnd(Terminator terminator) throws InvalidSyntaxException {
+ if (terminator.hasEndSequence())
+ currentIndex = getEndSequenceIndex(terminator) + terminator.endSequence.length();
+ else
+ currentIndex += terminator.startSequence.length();
+ }
+
+ private TokenizerMatch buildPreservedToken(StringBuilder token, Terminator terminator) throws InvalidSyntaxException {
+ if (hasAccumulatedToken(token))
+ return new TokenizerMatch(token.toString(), null, terminator);
+
+ if (terminator.hasEndSequence())
+ return buildComplexPreservedToken(terminator);
+ else
+ return buildSimplePreservedToken(terminator);
+ }
+
+ private TokenizerMatch buildSimplePreservedToken(Terminator terminator) {
+ currentIndex += terminator.startSequence.length();
+ return new TokenizerMatch(terminator.startSequence, null, terminator);
+ }
+
+ private TokenizerMatch buildComplexPreservedToken(Terminator terminator) throws InvalidSyntaxException {
+ int endSequenceIndex = getEndSequenceIndex(terminator);
+ String reminder = source.substring(currentIndex + terminator.startSequence.length(), endSequenceIndex);
+ currentIndex = endSequenceIndex + terminator.endSequence.length();
+
+ return new TokenizerMatch(terminator.startSequence, reminder, terminator);
+ }
+
+ private int getEndSequenceIndex(Terminator terminator) throws InvalidSyntaxException {
+ int endSequenceIndex = source.indexOf(terminator.endSequence,
+ currentIndex + terminator.startSequence.length());
+
+ if (endSequenceIndex < 0)
+ throw new InvalidSyntaxException("Expected \"" + terminator.endSequence + "\" but not found.");
+
+ return endSequenceIndex;
+ }
+
private boolean hasAccumulatedToken(StringBuilder token) {
return token.length() > 0;
}
- private boolean isTokenTermination() {
- return findTokenTerminator() != null;
+ private boolean isOngoingToken() {
+ return getOrFindTokenTerminator() == null;
}
- public Terminator findTokenTerminator() {
+ public boolean hasMoreTokens() {
+ return currentIndex < source.length();
+ }
+
+ /**
+ * Attempts to cache terminator search result.
+ */
+ public Terminator getOrFindTokenTerminator() {
+ if (currentIndex == cachedTerminatorIndex)
+ return cachedTerminator;
+
+ cachedTerminatorIndex = currentIndex;
+ cachedTerminator = findTokenTerminator();
+ return cachedTerminator;
+ }
+
+ private Terminator findTokenTerminator() {
for (Terminator terminator : terminators)
if (terminator.matches(source, currentIndex))
return terminator;
return null;
}
- public boolean consumeIfNextToken(final String token) {
+ public boolean consumeIfNextToken(final String token) throws InvalidSyntaxException {
if (token.equals(getNextToken().token))
return true;
return false;
}
- public TokenizerMatch peekNextToken(){
+ public TokenizerMatch peekNextToken() throws InvalidSyntaxException {
TokenizerMatch result = getNextToken();
unreadToken();
return result;
}
- public boolean peekIsOneOf(String ... possibilities){
+ public boolean peekIsOneOf(String... possibilities) throws InvalidSyntaxException {
String nextToken = peekNextToken().token;
return Stream.of(possibilities).anyMatch(possibility -> possibility.equals(nextToken));
}
- public void peekExpectNoneOf(String ... possibilities) throws InvalidSyntaxException {
+ public void peekExpectNoneOf(String... possibilities) throws InvalidSyntaxException {
if (peekIsOneOf(possibilities))
throw new InvalidSyntaxException("Not expected \"" + peekNextToken().token + "\" here.");
}
-
- public boolean sequenceMatches(final String sequence) {
- if ((currentIndex + sequence.length()) > source.length())
- return false;
-
- for (int i = 0; i < sequence.length(); i++)
- if (sequence.charAt(i) != source.charAt(i + currentIndex))
- return false;
-
- return true;
+ public void unreadToken() {
+ currentIndex = tokenIndexes.pop();
}
public void skipUntilDataEnd() {
currentIndex = source.length();
}
- public void skipUntilSequence(final String sequence) {
- while (currentIndex < source.length()) {
- if (sequenceMatches(sequence)) {
- currentIndex += sequence.length();
- return;
- }
-
- currentIndex++;
- }
- }
-
- public void unreadToken() {
- currentIndex = tokenIndexes.pop();
- }
-
}