public void translateLeftRecursiveRules() {
String language = g.getOptionString("language");
// translate all recursive rules
List<String> leftRecursiveRuleNames = new ArrayList<String>();
for (Rule r : rules) {
if (!Grammar.isTokenName(r.name)) {
if (LeftRecursiveRuleAnalyzer.hasImmediateRecursiveRuleRefs(r.ast, r.name)) {
g.originalTokenStream = g.tokenStream;
boolean fitsPattern = translateLeftRecursiveRule(ast, (LeftRecursiveRule) r, language);
if (fitsPattern) leftRecursiveRuleNames.add(r.name);
}
}
}
// update all refs to recursive rules to have [0] argument
for (GrammarAST r : ast.getNodesWithType(ANTLRParser.RULE_REF)) {
if (r.getParent().getType() == ANTLRParser.RULE) continue; // must be rule def
if (((GrammarASTWithOptions) r).getOptionString(PRECEDENCE_OPTION_NAME) != null)
continue; // already has arg; must be in rewritten rule
if (leftRecursiveRuleNames.contains(r.getText())) {
// found ref to recursive rule not already rewritten with arg
((GrammarASTWithOptions) r)
.setOption(
PRECEDENCE_OPTION_NAME,
(GrammarAST) new GrammarASTAdaptor().create(ANTLRParser.INT, "0"));
}
}
}
/** Return true if successful */
public boolean translateLeftRecursiveRule(
GrammarRootAST ast, LeftRecursiveRule r, String language) {
// tool.log("grammar", ruleAST.toStringTree());
GrammarAST prevRuleAST = r.ast;
String ruleName = prevRuleAST.getChild(0).getText();
LeftRecursiveRuleAnalyzer leftRecursiveRuleWalker =
new LeftRecursiveRuleAnalyzer(prevRuleAST, tool, ruleName, language);
boolean isLeftRec;
try {
// System.out.println("TESTING ---------------\n"+
// leftRecursiveRuleWalker.text(ruleAST));
isLeftRec = leftRecursiveRuleWalker.rec_rule();
} catch (RecognitionException re) {
isLeftRec = false; // didn't match; oh well
}
if (!isLeftRec) return false;
// replace old rule's AST
GrammarAST RULES = (GrammarAST) ast.getFirstChildWithType(ANTLRParser.RULES);
String newRuleText = leftRecursiveRuleWalker.getArtificialOpPrecRule();
// System.out.println("created: "+newRuleText);
RuleAST t = parseArtificialRule(g, newRuleText);
// reuse the name token from the original AST since it refers to the proper source location in
// the original grammar
((GrammarAST) t.getChild(0)).token = ((GrammarAST) prevRuleAST.getChild(0)).getToken();
// update grammar AST and set rule's AST.
RULES.setChild(prevRuleAST.getChildIndex(), t);
r.ast = t;
// Reduce sets in newly created rule tree
GrammarTransformPipeline transform = new GrammarTransformPipeline(g, g.tool);
transform.reduceBlocksToSets(r.ast);
transform.expandParameterizedLoops(r.ast);
// Rerun semantic checks on the new rule
RuleCollector ruleCollector = new RuleCollector(g);
ruleCollector.visit(t, "rule");
BasicSemanticChecks basics = new BasicSemanticChecks(g, ruleCollector);
// disable the assoc element option checks because they are already
// handled for the pre-transformed rule.
basics.checkAssocElementOption = false;
basics.visit(t, "rule");
// track recursive alt info for codegen
r.recPrimaryAlts = new ArrayList<LeftRecursiveRuleAltInfo>();
r.recPrimaryAlts.addAll(leftRecursiveRuleWalker.prefixAlts);
r.recPrimaryAlts.addAll(leftRecursiveRuleWalker.otherAlts);
if (r.recPrimaryAlts.isEmpty()) {
tool.errMgr.grammarError(
ErrorType.NO_NON_LR_ALTS,
g.fileName,
((GrammarAST) r.ast.getChild(0)).getToken(),
r.name);
}
r.recOpAlts = new OrderedHashMap<Integer, LeftRecursiveRuleAltInfo>();
r.recOpAlts.putAll(leftRecursiveRuleWalker.binaryAlts);
r.recOpAlts.putAll(leftRecursiveRuleWalker.ternaryAlts);
r.recOpAlts.putAll(leftRecursiveRuleWalker.suffixAlts);
// walk alt info records and set their altAST to point to appropriate ALT subtree
// from freshly created AST
setAltASTPointers(r, t);
// update Rule to just one alt and add prec alt
ActionAST arg = (ActionAST) r.ast.getFirstChildWithType(ANTLRParser.ARG_ACTION);
if (arg != null) {
r.args = ScopeParser.parseTypedArgList(arg, arg.getText(), g.tool.errMgr);
r.args.type = AttributeDict.DictType.ARG;
r.args.ast = arg;
arg.resolver = r.alt[1]; // todo: isn't this Rule or something?
}
// define labels on recursive rule refs we delete; they don't point to nodes of course
// these are so $label in action translation works
for (Pair<GrammarAST, String> pair : leftRecursiveRuleWalker.leftRecursiveRuleRefLabels) {
GrammarAST labelNode = pair.a;
GrammarAST labelOpNode = (GrammarAST) labelNode.getParent();
GrammarAST elementNode = (GrammarAST) labelOpNode.getChild(1);
LabelElementPair lp = new LabelElementPair(g, labelNode, elementNode, labelOpNode.getType());
r.alt[1].labelDefs.map(labelNode.getText(), lp);
}
// copy to rule from walker
r.leftRecursiveRuleRefLabels = leftRecursiveRuleWalker.leftRecursiveRuleRefLabels;
tool.log("grammar", "added: " + t.toStringTree());
return true;
}
