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Regex: implement alternatives

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Now we support regular expressions like 'A|B|C'.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This commit is contained in:
Johannes Schindelin 2013-11-11 23:09:25 -06:00
parent c3a06a600a
commit d4a2f58eb5
2 changed files with 38 additions and 3 deletions
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2
test/Regex.java
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@ -57,5 +57,7 @@ public class Regex {
expectMatch("[0-9A-Fa-f]+", "08ef"); expectMatch("[0-9A-Fa-f]+", "08ef");
expectNoMatch("[0-9A-Fa-f]+", "08@ef"); expectNoMatch("[0-9A-Fa-f]+", "08@ef");
expectGroups("(?:a)", "a"); expectGroups("(?:a)", "a");
expectGroups("a|(b|c)", "a", (String)null);
expectGroups("a|(b|c)", "c", "c");
} }
} }

39
test/regex/Compiler.java
View File

@ -143,9 +143,13 @@ class Compiler implements PikeVMOpcodes {
private final boolean capturing; private final boolean capturing;
private ArrayList<Expression> list = new ArrayList<Expression>(); private ArrayList<Expression> list = new ArrayList<Expression>();
private ArrayList<Group> alternatives;
public Group(boolean capturing) { public Group(boolean capturing, ArrayList<Expression> initialList) {
this.capturing = capturing; this.capturing = capturing;
if (initialList != null) {
list.addAll(initialList);
}
} }
public void push(Expression expr) { public void push(Expression expr) {
@ -160,6 +164,14 @@ class Compiler implements PikeVMOpcodes {
}); });
} }
public void startAlternative() {
if (alternatives == null) {
alternatives = new ArrayList<Group>();
}
alternatives.add(new Group(false, list));
list.clear();
}
public Expression pop() { public Expression pop() {
Expression result = list.remove(list.size() - 1); Expression result = list.remove(list.size() - 1);
return result; return result;
@ -172,9 +184,27 @@ class Compiler implements PikeVMOpcodes {
output.add(SAVE_OFFSET); output.add(SAVE_OFFSET);
output.add(2 * groupIndex); output.add(2 * groupIndex);
} }
int[] jumps = null;
if (alternatives != null) {
jumps = new int[alternatives.size()];
int i = 0;
for (Group alternative : alternatives) {
output.add(SPLIT);
int jump = output.markJump();
alternative.writeCode(output);
output.add(JMP);
jumps[i++] = output.markJump();
output.setJump(jump);
}
}
for (Expression expr : list) { for (Expression expr : list) {
expr.writeCode(output); expr.writeCode(output);
} }
if (jumps != null) {
for (int jump : jumps) {
output.setJump(jump);
}
}
if (capturing) { if (capturing) {
output.add(SAVE_OFFSET); output.add(SAVE_OFFSET);
output.add(2 * groupIndex + 1); output.add(2 * groupIndex + 1);
@ -186,7 +216,7 @@ class Compiler implements PikeVMOpcodes {
private final Group group; private final Group group;
public Group0() { public Group0() {
group = new Group(true); group = new Group(true, null);
} }
public void writeCode(Output output) { public void writeCode(Output output) {
@ -249,7 +279,7 @@ class Compiler implements PikeVMOpcodes {
+ regex.substring(index)); + regex.substring(index));
} }
} }
current.push(groups.push(new Group(capturing))); current.push(groups.push(new Group(capturing, null)));
continue; continue;
} }
case ')': case ')':
@ -268,6 +298,9 @@ class Compiler implements PikeVMOpcodes {
index = characterClassParser.getEndOffset() - 1; index = characterClassParser.getEndOffset() - 1;
continue; continue;
} }
case '|':
current.startAlternative();
continue;
default: default:
throw new RuntimeException("Parse error @" + index + ": " + regex); throw new RuntimeException("Parse error @" + index + ": " + regex);
} }