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    • org.antlr.codegen.CodeGenerator Maven / Gradle / Ivy

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    /*
 * [The "BSD license"]
 *  Copyright (c) 2010 Terence Parr
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.antlr.codegen;


import org.antlr.Tool;
import org.antlr.analysis.DFA;
import org.antlr.analysis.*;
import org.antlr.grammar.v3.ANTLRLexer;
import org.antlr.grammar.v3.ANTLRParser;
import org.antlr.grammar.v3.ActionTranslator;
import org.antlr.grammar.v3.CodeGenTreeWalker;
import org.antlr.misc.BitSet;
import org.antlr.misc.*;
import org.antlr.runtime.*;
import org.antlr.runtime.tree.CommonTreeNodeStream;
import org.antlr.tool.*;
import org.stringtemplate.v4.*;

import java.io.IOException;
import java.io.Writer;
import java.util.*;

/** ANTLR's code generator.
 *
 *  Generate recognizers derived from grammars.  Language independence
 *  achieved through the use of STGroup objects.  All output
 *  strings are completely encapsulated in the group files such as Java.stg.
 *  Some computations are done that are unused by a particular language.
 *  This generator just computes and sets the values into the templates;
 *  the templates are free to use or not use the information.
 *
 *  To make a new code generation target, define X.stg for language X
 *  by copying from existing Y.stg most closely releated to your language;
 *  e.g., to do CSharp.stg copy Java.stg.  The template group file has a
 *  bunch of templates that are needed by the code generator.  You can add
 *  a new target w/o even recompiling ANTLR itself.  The language=X option
 *  in a grammar file dictates which templates get loaded/used.
 *
 *  Some language like C need both parser files and header files.  Java needs
 *  to have a separate file for the cyclic DFA as ANTLR generates bytecodes
 *  directly (which cannot be in the generated parser Java file).  To facilitate
 *  this,
 *
 * cyclic can be in same file, but header, output must be searpate.  recognizer
 *  is in outptufile.
 */
public class CodeGenerator {
	/** When generating SWITCH statements, some targets might need to limit
	 *  the size (based upon the number of case labels).  Generally, this
	 *  limit will be hit only for lexers where wildcard in a UNICODE
	 *  vocabulary environment would generate a SWITCH with 65000 labels.
	 */
	public final static int MSCL_DEFAULT = 300;
	public static int MAX_SWITCH_CASE_LABELS = MSCL_DEFAULT;
	public final static int MSA_DEFAULT = 3;
	public static int MIN_SWITCH_ALTS = MSA_DEFAULT;
	public boolean GENERATE_SWITCHES_WHEN_POSSIBLE = true;
	public static boolean LAUNCH_ST_INSPECTOR = false;
	public final static int MADSI_DEFAULT = 60; // do lots of states inline (needed for expression rules)
	public static int MAX_ACYCLIC_DFA_STATES_INLINE = MADSI_DEFAULT;

	public static String classpathTemplateRootDirectoryName =
		"org/antlr/codegen/templates";

	/** Which grammar are we generating code for?  Each generator
	 *  is attached to a specific grammar.
	 */
	public Grammar grammar;

	/** What language are we generating? */
	protected String language;

	/** The target specifies how to write out files and do other language
	 *  specific actions.
	 */
	public Target target = null;

	/** Where are the templates this generator should use to generate code? */
	protected STGroup templates;

	/** The basic output templates without AST or templates stuff; this will be
	 *  the templates loaded for the language such as Java.stg *and* the Dbg
	 *  stuff if turned on.  This is used for generating syntactic predicates.
	 */
	protected STGroup baseTemplates;

	protected ST recognizerST;
	protected ST outputFileST;
	protected ST headerFileST;

	/** Used to create unique labels */
	protected int uniqueLabelNumber = 1;

	/** A reference to the ANTLR tool so we can learn about output directories
	 *  and such.
	 */
	protected Tool tool;

	/** Generate debugging event method calls */
	protected boolean debug;

	/** Create a Tracer object and make the recognizer invoke this. */
	protected boolean trace;

	/** Track runtime parsing information about decisions etc...
	 *  This requires the debugging event mechanism to work.
	 */
	protected boolean profile;

	protected int lineWidth = 72;

	/** I have factored out the generation of acyclic DFAs to separate class */
	public ACyclicDFACodeGenerator acyclicDFAGenerator =
		new ACyclicDFACodeGenerator(this);

	/** I have factored out the generation of cyclic DFAs to separate class */
	/*
	public CyclicDFACodeGenerator cyclicDFAGenerator =
		new CyclicDFACodeGenerator(this);
		*/

	public static final String VOCAB_FILE_EXTENSION = ".tokens";
	protected final static String vocabFilePattern =
		"=\n}>" +
		"=\n}>";

	public CodeGenerator(Tool tool, Grammar grammar, String language) {
		this.tool = tool;
		this.grammar = grammar;
		this.language = language;
		target = loadLanguageTarget(language);
	}

	public static Target loadLanguageTarget(String language) {
		Target target = null;
		String targetName = "org.antlr.codegen."+language+"Target";
		try {
			Class c = Class.forName(targetName).asSubclass(Target.class);
			target = (Target)c.newInstance();
		}
		catch (ClassNotFoundException cnfe) {
			target = new Target(); // use default
		}
		catch (InstantiationException ie) {
			ErrorManager.error(ErrorManager.MSG_CANNOT_CREATE_TARGET_GENERATOR,
							   targetName,
							   ie);
		}
		catch (IllegalAccessException cnfe) {
			ErrorManager.error(ErrorManager.MSG_CANNOT_CREATE_TARGET_GENERATOR,
							   targetName,
							   cnfe);
		}
		return target;
	}

	/** load the main language.stg template group file */
	public void loadTemplates(String language) {
		String langDir = classpathTemplateRootDirectoryName+"/"+language;
		STGroup coreTemplates = new ToolSTGroupFile(langDir+"/"+language+".stg");
		baseTemplates = coreTemplates;

		// dynamically add subgroups that act like filters to apply to
		// their supergroup.  E.g., Java:Dbg:AST:ASTParser::ASTDbg.
		String outputOption = (String)grammar.getOption("output");
		if ( outputOption!=null && outputOption.equals("AST") ) {
			if ( debug && grammar.type!=Grammar.LEXER ) {
				STGroup dbgTemplates = new ToolSTGroupFile(langDir+"/Dbg.stg");
				dbgTemplates.importTemplates(coreTemplates);
				baseTemplates = dbgTemplates;
				STGroup astTemplates = new ToolSTGroupFile(langDir+"/AST.stg");
				astTemplates.importTemplates(dbgTemplates);
				STGroup astParserTemplates;
				if ( grammar.type==Grammar.TREE_PARSER ) {
					astParserTemplates = new ToolSTGroupFile(langDir+"/ASTTreeParser.stg");
					astParserTemplates.importTemplates(astTemplates);
				}
				else {
					astParserTemplates = new ToolSTGroupFile(langDir+"/ASTParser.stg");
					astParserTemplates.importTemplates(astTemplates);
				}
				STGroup astDbgTemplates = new ToolSTGroupFile(langDir+"/ASTDbg.stg");
				astDbgTemplates.importTemplates(astParserTemplates);
				templates = astDbgTemplates;
				dbgTemplates.iterateAcrossValues = true; // ST v3 compatibility with Maps
				astDbgTemplates.iterateAcrossValues = true;
				astParserTemplates.iterateAcrossValues = true;
			}
			else {
				STGroup astTemplates = new ToolSTGroupFile(langDir+"/AST.stg");
				astTemplates.importTemplates(coreTemplates);
				STGroup astParserTemplates;
				if ( grammar.type==Grammar.TREE_PARSER ) {
					astParserTemplates = new ToolSTGroupFile(langDir+"/ASTTreeParser.stg");
					astParserTemplates.importTemplates(astTemplates);
				}
				else {
					astParserTemplates = new ToolSTGroupFile(langDir+"/ASTParser.stg");
					astParserTemplates.importTemplates(astTemplates);
				}
				templates = astParserTemplates;
				astTemplates.iterateAcrossValues = true; // ST v3 compatibility with Maps
				astParserTemplates.iterateAcrossValues = true;
			}
		}
		else if ( outputOption!=null && outputOption.equals("template") ) {
			if ( debug && grammar.type!=Grammar.LEXER ) {
				STGroup dbgTemplates = new ToolSTGroupFile(langDir+"/Dbg.stg");
				dbgTemplates.importTemplates(coreTemplates);
				baseTemplates = dbgTemplates;
				STGroup stTemplates = new ToolSTGroupFile(langDir+"/ST.stg");
				stTemplates.importTemplates(dbgTemplates);
				templates = stTemplates;
				dbgTemplates.iterateAcrossValues = true;
			}
			else {
				STGroup stTemplates = new ToolSTGroupFile(langDir+"/ST.stg");
				stTemplates.importTemplates(coreTemplates);
				templates = stTemplates;
			}
			templates.iterateAcrossValues = true; // ST v3 compatibility with Maps
		}
		else if ( debug && grammar.type!=Grammar.LEXER ) {
			STGroup dbgTemplates = new ToolSTGroupFile(langDir+"/Dbg.stg");
			dbgTemplates.importTemplates(coreTemplates);
			templates = dbgTemplates;
			baseTemplates = templates;
			baseTemplates.iterateAcrossValues = true; // ST v3 compatibility with Maps
		}
		else {
			templates = coreTemplates;
			coreTemplates.iterateAcrossValues = true; // ST v3 compatibility with Maps
		}
	}

	/** Given the grammar to which we are attached, walk the AST associated
	 *  with that grammar to create NFAs.  Then create the DFAs for all
	 *  decision points in the grammar by converting the NFAs to DFAs.
	 *  Finally, walk the AST again to generate code.
	 *
	 *  Either 1 or 2 files are written:
	 *
	 * 		recognizer: the main parser/lexer/treewalker item
	 * 		header file: language like C/C++ need extern definitions
	 *
	 *  The target, such as JavaTarget, dictates which files get written.
	 */
	public ST genRecognizer() {
		//System.out.println("### generate "+grammar.name+" recognizer");
		// LOAD OUTPUT TEMPLATES
		loadTemplates(language);
		if ( templates==null ) {
			return null;
		}

		// CREATE NFA FROM GRAMMAR, CREATE DFA FROM NFA
		if ( ErrorManager.doNotAttemptAnalysis() ) {
			return null;
		}
		target.performGrammarAnalysis(this, grammar);


		// some grammar analysis errors will not yield reliable DFA
		if ( ErrorManager.doNotAttemptCodeGen() ) {
			return null;
		}

		// OPTIMIZE DFA
		DFAOptimizer optimizer = new DFAOptimizer(grammar);
		optimizer.optimize();

		// OUTPUT FILE (contains recognizerST)
		outputFileST = templates.getInstanceOf("outputFile");

		// HEADER FILE
		if ( templates.isDefined("headerFile") ) {
			headerFileST = templates.getInstanceOf("headerFile");
		}
		else {
			// create a dummy to avoid null-checks all over code generator
			headerFileST = new ST(templates,"xyz");
			headerFileST.add("cyclicDFAs", (Object)null); // it normally sees this from outputFile
			//headerFileST.impl.name = "dummy-header-file";
		}

		boolean filterMode = grammar.getOption("filter")!=null &&
							  grammar.getOption("filter").equals("true");
        boolean canBacktrack = grammar.getSyntacticPredicates()!=null ||
                               grammar.composite.getRootGrammar().atLeastOneBacktrackOption ||
                               filterMode;

        // TODO: move this down further because generating the recognizer
		// alters the model with info on who uses predefined properties etc...
		// The actions here might refer to something.

		// The only two possible output files are available at this point.
		// Verify action scopes are ok for target and dump actions into output
		// Templates can say  for example.
		Map> actions = grammar.getActions();
		verifyActionScopesOkForTarget(actions);
		// translate $x::y references
		translateActionAttributeReferences(actions);

        ST gateST = templates.getInstanceOf("actionGate");
        if ( filterMode ) {
            // if filtering, we need to set actions to execute at backtracking
            // level 1 not 0.
            gateST = templates.getInstanceOf("filteringActionGate");
        }
        grammar.setSynPredGateIfNotAlready(gateST);

        headerFileST.add("actions", actions);
		outputFileST.add("actions", actions);

		headerFileST.add("buildTemplate", grammar.buildTemplate());
		outputFileST.add("buildTemplate", grammar.buildTemplate());
		headerFileST.add("buildAST", grammar.buildAST());
		outputFileST.add("buildAST", grammar.buildAST());

		outputFileST.add("rewriteMode", grammar.rewriteMode());
		headerFileST.add("rewriteMode", grammar.rewriteMode());

		outputFileST.add("backtracking", canBacktrack);
		headerFileST.add("backtracking", canBacktrack);
		// turn on memoize attribute at grammar level so we can create ruleMemo.
		// each rule has memoize attr that hides this one, indicating whether
		// it needs to save results
		String memoize = (String)grammar.getOption("memoize");
		outputFileST.add("memoize",
						 (grammar.atLeastOneRuleMemoizes ||
						  memoize != null && memoize.equals("true") &&
						  canBacktrack));
		headerFileST.add("memoize",
						 (grammar.atLeastOneRuleMemoizes ||
						  memoize != null && memoize.equals("true") &&
						  canBacktrack));


		outputFileST.add("trace", trace);
		headerFileST.add("trace", trace);

		outputFileST.add("profile", profile);
		headerFileST.add("profile", profile);

		// RECOGNIZER
		if ( grammar.type==Grammar.LEXER ) {
			recognizerST = templates.getInstanceOf("lexer");
			outputFileST.add("LEXER", true);
			headerFileST.add("LEXER", true);
			recognizerST.add("filterMode",
							 filterMode);
		}
		else if ( grammar.type==Grammar.PARSER ||
			grammar.type==Grammar.COMBINED )
		{
			recognizerST = templates.getInstanceOf("parser");
			outputFileST.add("PARSER", true);
			headerFileST.add("PARSER", true);
		}
		else {
			recognizerST = templates.getInstanceOf("treeParser");
			outputFileST.add("TREE_PARSER", true);
			headerFileST.add("TREE_PARSER", true);
            recognizerST.add("filterMode",
							 filterMode);
		}
		outputFileST.add("recognizer", recognizerST);
		headerFileST.add("recognizer", recognizerST);
		outputFileST.add("actionScope",
						 grammar.getDefaultActionScope(grammar.type));
		headerFileST.add("actionScope",
						 grammar.getDefaultActionScope(grammar.type));

		String targetAppropriateFileNameString =
			target.getTargetStringLiteralFromString(grammar.getFileName());
		outputFileST.add("fileName", targetAppropriateFileNameString);
		headerFileST.add("fileName", targetAppropriateFileNameString);
		outputFileST.add("ANTLRVersion", tool.VERSION);
		headerFileST.add("ANTLRVersion", tool.VERSION);
		outputFileST.add("generatedTimestamp", Tool.getCurrentTimeStamp());
		headerFileST.add("generatedTimestamp", Tool.getCurrentTimeStamp());

		// GENERATE RECOGNIZER
		// Walk the AST holding the input grammar, this time generating code
		// Decisions are generated by using the precomputed DFAs
		// Fill in the various templates with data
		CodeGenTreeWalker gen = new CodeGenTreeWalker(new CommonTreeNodeStream(grammar.getGrammarTree()));
		try {
			gen.grammar_(
						grammar,
						recognizerST,
						outputFileST,
						headerFileST);
		}
		catch (RecognitionException re) {
			ErrorManager.error(ErrorManager.MSG_BAD_AST_STRUCTURE,
							   re);
		}

		genTokenTypeConstants(recognizerST);
		genTokenTypeConstants(outputFileST);
		genTokenTypeConstants(headerFileST);

		if ( grammar.type!=Grammar.LEXER ) {
			genTokenTypeNames(recognizerST);
			genTokenTypeNames(outputFileST);
			genTokenTypeNames(headerFileST);
		}

		// Now that we know what synpreds are used, we can set into template
		Set synpredNames = null;
		if ( grammar.synPredNamesUsedInDFA.size()>0 ) {
			synpredNames = grammar.synPredNamesUsedInDFA;
		}
		outputFileST.add("synpreds", synpredNames);
		headerFileST.add("synpreds", synpredNames);

		// all recognizers can see Grammar object
		recognizerST.add("grammar", grammar);

		// do not render templates to disk if errors occurred
		if ( ErrorManager.getErrorState().errors > 0 ) {
			return null;
		}

		if (LAUNCH_ST_INSPECTOR) {
			outputFileST.inspect();
			if ( templates.isDefined("headerFile") ) headerFileST.inspect();
		}

		// WRITE FILES
		try {
			target.genRecognizerFile(tool,this,grammar,outputFileST);
			if ( templates.isDefined("headerFile") ) {
				ST extST = templates.getInstanceOf("headerFileExtension");
				target.genRecognizerHeaderFile(tool,this,grammar,headerFileST,extST.render());
			}
			// write out the vocab interchange file; used by antlr,
			// does not change per target
			ST tokenVocabSerialization = genTokenVocabOutput();
			String vocabFileName = getVocabFileName();
			if ( vocabFileName!=null ) {
				write(tokenVocabSerialization, vocabFileName);
			}
			//System.out.println(outputFileST.getDOTForDependencyGraph(false));
		}
		catch (IOException ioe) {
			ErrorManager.error(ErrorManager.MSG_CANNOT_WRITE_FILE, ioe);
		}
		/*
		System.out.println("num obj.prop refs: "+ ASTExpr.totalObjPropRefs);
		System.out.println("num reflection lookups: "+ ASTExpr.totalReflectionLookups);
		*/

		return outputFileST;
	}

	/** Some targets will have some extra scopes like C++ may have
	 *  '@headerfile:name {action}' or something.  Make sure the
	 *  target likes the scopes in action table.
	 */
	protected void verifyActionScopesOkForTarget(Map> actions) {
		for (Map.Entry> entry : actions.entrySet()) {
			String scope = entry.getKey();
			if ( !target.isValidActionScope(grammar.type, scope) ) {
				// get any action from the scope to get error location
				Map scopeActions = entry.getValue();
				GrammarAST actionAST =
					(GrammarAST)scopeActions.values().iterator().next();
				ErrorManager.grammarError(
					ErrorManager.MSG_INVALID_ACTION_SCOPE,grammar,
					actionAST.getToken(),scope,
					grammar.getGrammarTypeString());
			}
		}
	}

	/** Actions may reference $x::y attributes, call translateAction on
	 *  each action and replace that action in the Map.
	 */
	protected void translateActionAttributeReferences(Map> actions) {
		for (Map.Entry> entry : actions.entrySet()) {
			Map scopeActions = entry.getValue();
			translateActionAttributeReferencesForSingleScope(null,scopeActions);
		}
	}

	/** Use for translating rule @init{...} actions that have no scope */
	public void translateActionAttributeReferencesForSingleScope(
		Rule r,
		Map scopeActions)
	{
		String ruleName=null;
		if ( r!=null ) {
			ruleName = r.name;
		}
		for (Map.Entry entry : scopeActions.entrySet()) {
			String name = entry.getKey();
			GrammarAST actionAST = (GrammarAST)entry.getValue();
			List chunks = translateAction(ruleName,actionAST);
			scopeActions.put(name, chunks); // replace with translation
		}
	}

	/** Error recovery in ANTLR recognizers.
	 *
	 *  Based upon original ideas:
	 *
	 *  Algorithms + Data Structures = Programs by Niklaus Wirth
	 *
	 *  and
	 *
	 *  A note on error recovery in recursive descent parsers:
	 *  http://portal.acm.org/citation.cfm?id=947902.947905
	 *
	 *  Later, Josef Grosch had some good ideas:
	 *  Efficient and Comfortable Error Recovery in Recursive Descent Parsers:
	 *  ftp://www.cocolab.com/products/cocktail/doca4.ps/ell.ps.zip
	 *
	 *  Like Grosch I implemented local FOLLOW sets that are combined at run-time
	 *  upon error to avoid parsing overhead.
	 */
	public void generateLocalFOLLOW(GrammarAST referencedElementNode,
									String referencedElementName,
									String enclosingRuleName,
									int elementIndex)
	{
		/*
		System.out.println("compute FOLLOW "+grammar.name+"."+referencedElementNode.toString()+
						 " for "+referencedElementName+"#"+elementIndex +" in "+
						 enclosingRuleName+
						 " line="+referencedElementNode.getLine());
						 */
		NFAState followingNFAState = referencedElementNode.followingNFAState;
		LookaheadSet follow = null;
		if ( followingNFAState!=null ) {
			// compute follow for this element and, as side-effect, track
			// the rule LOOK sensitivity.
			follow = grammar.FIRST(followingNFAState);
		}

		if ( follow==null ) {
			ErrorManager.internalError("no follow state or cannot compute follow");
			follow = new LookaheadSet();
		}
		if ( follow.member(Label.EOF) ) {
			// TODO: can we just remove?  Seems needed here:
			// compilation_unit : global_statement* EOF
			// Actually i guess we resync to EOF regardless
			follow.remove(Label.EOF);
		}
		//System.out.println(" "+follow);

        List tokenTypeList;
        long[] words;
		if ( follow.tokenTypeSet==null ) {
			words = new long[1];
            tokenTypeList = new ArrayList();
        }
		else {
			BitSet bits = BitSet.of(follow.tokenTypeSet);
			words = bits.toPackedArray();
            tokenTypeList = follow.tokenTypeSet.toList();
        }
		// use the target to convert to hex strings (typically)
		String[] wordStrings = new String[words.length];
		for (int j = 0; j < words.length; j++) {
			long w = words[j];
			wordStrings[j] = target.getTarget64BitStringFromValue(w);
		}
		recognizerST.addAggr("bitsets.{name,inName,bits,tokenTypes,tokenIndex}",
							 referencedElementName,
							 enclosingRuleName,
							 wordStrings,
							 tokenTypeList,
							 Utils.integer(elementIndex));
		outputFileST.addAggr("bitsets.{name,inName,bits,tokenTypes,tokenIndex}",
							 referencedElementName,
							 enclosingRuleName,
							 wordStrings,
							 tokenTypeList,
							 Utils.integer(elementIndex));
		headerFileST.addAggr("bitsets.{name,inName,bits,tokenTypes,tokenIndex}",
							 referencedElementName,
							 enclosingRuleName,
							 wordStrings,
							 tokenTypeList,
							 Utils.integer(elementIndex));
	}

	// L O O K A H E A D  D E C I S I O N  G E N E R A T I O N

	/** Generate code that computes the predicted alt given a DFA.  The
	 *  recognizerST can be either the main generated recognizerTemplate
	 *  for storage in the main parser file or a separate file.  It's up to
	 *  the code that ultimately invokes the codegen.g grammar rule.
	 *
	 *  Regardless, the output file and header file get a copy of the DFAs.
	 */
	public ST genLookaheadDecision(ST recognizerST,
								   DFA dfa)
	{
		ST decisionST;
		// If we are doing inline DFA and this one is acyclic and LL(*)
		// I have to check for is-non-LL(*) because if non-LL(*) the cyclic
		// check is not done by DFA.verify(); that is, verify() avoids
		// doesStateReachAcceptState() if non-LL(*)
		if ( dfa.canInlineDecision() ) {
			decisionST =
				acyclicDFAGenerator.genFixedLookaheadDecision(getTemplates(), dfa);
		}
		else {
			// generate any kind of DFA here (cyclic or acyclic)
			dfa.createStateTables(this);
			outputFileST.add("cyclicDFAs", dfa);
			headerFileST.add("cyclicDFAs", dfa);
			decisionST = templates.getInstanceOf("dfaDecision");
			String description = dfa.getNFADecisionStartState().getDescription();
			description = target.getTargetStringLiteralFromString(description);
			if ( description!=null ) {
				decisionST.add("description", description);
			}
			decisionST.add("decisionNumber",
						   Utils.integer(dfa.getDecisionNumber()));
		}
		return decisionST;
	}

	/** A special state is huge (too big for state tables) or has a predicated
	 *  edge.  Generate a simple if-then-else.  Cannot be an accept state as
	 *  they have no emanating edges.  Don't worry about switch vs if-then-else
	 *  because if you get here, the state is super complicated and needs an
	 *  if-then-else.  This is used by the new DFA scheme created June 2006.
	 */
	public ST generateSpecialState(DFAState s) {
		ST stateST;
		stateST = templates.getInstanceOf("cyclicDFAState");
		stateST.add("needErrorClause", true);
		stateST.add("semPredState",
					s.isResolvedWithPredicates());
		stateST.add("stateNumber", s.stateNumber);
		stateST.add("decisionNumber", s.dfa.decisionNumber);

		boolean foundGatedPred = false;
		ST eotST = null;
		for (int i = 0; i < s.getNumberOfTransitions(); i++) {
			Transition edge = s.transition(i);
			ST edgeST;
			if ( edge.label.getAtom()==Label.EOT ) {
				// this is the default clause; has to held until last
				edgeST = templates.getInstanceOf("eotDFAEdge");
				stateST.remove("needErrorClause");
				eotST = edgeST;
			}
			else {
				edgeST = templates.getInstanceOf("cyclicDFAEdge");
				ST exprST =
					genLabelExpr(templates,edge,1);
				edgeST.add("labelExpr", exprST);
			}
			edgeST.add("edgeNumber", Utils.integer(i + 1));
			edgeST.add("targetStateNumber",
					   Utils.integer(edge.target.stateNumber));
			// stick in any gated predicates for any edge if not already a pred
			if ( !edge.label.isSemanticPredicate() ) {
				DFAState t = (DFAState)edge.target;
				SemanticContext preds =	t.getGatedPredicatesInNFAConfigurations();
				if ( preds!=null ) {
					foundGatedPred = true;
					ST predST = preds.genExpr(this,
														  getTemplates(),
														  t.dfa);
					edgeST.add("predicates", predST.render());
				}
			}
			if ( edge.label.getAtom()!=Label.EOT ) {
				stateST.add("edges", edgeST);
			}
		}
		if ( foundGatedPred ) {
			// state has >= 1 edge with a gated pred (syn or sem)
			// must rewind input first, set flag.
			stateST.add("semPredState", foundGatedPred);
		}
		if ( eotST!=null ) {
			stateST.add("edges", eotST);
		}
		return stateST;
	}

	/** Generate an expression for traversing an edge. */
	protected ST genLabelExpr(STGroup templates,
										  Transition edge,
										  int k)
	{
		Label label = edge.label;
		if ( label.isSemanticPredicate() ) {
			return genSemanticPredicateExpr(templates, edge);
		}
		if ( label.isSet() ) {
			return genSetExpr(templates, label.getSet(), k, true);
		}
		// must be simple label
		ST eST = templates.getInstanceOf("lookaheadTest");
		eST.add("atom", getTokenTypeAsTargetLabel(label.getAtom()));
		eST.add("atomAsInt", Utils.integer(label.getAtom()));
		eST.add("k", Utils.integer(k));
		return eST;
	}

	protected ST genSemanticPredicateExpr(STGroup templates,
													  Transition edge)
	{
		DFA dfa = ((DFAState)edge.target).dfa; // which DFA are we in
		Label label = edge.label;
		SemanticContext semCtx = label.getSemanticContext();
		return semCtx.genExpr(this,templates,dfa);
	}

	/** For intervals such as [3..3, 30..35], generate an expression that
	 *  tests the lookahead similar to LA(1)==3 || (LA(1)>=30&&LA(1)<=35)
	 */
	public ST genSetExpr(STGroup templates,
									 IntSet set,
									 int k,
									 boolean partOfDFA)
	{
		if ( !(set instanceof IntervalSet) ) {
			throw new IllegalArgumentException("unable to generate expressions for non IntervalSet objects");
		}
		IntervalSet iset = (IntervalSet)set;
		if ( iset.getIntervals()==null || iset.getIntervals().isEmpty() ) {
			ST emptyST = new ST(templates, "");
			emptyST.impl.name = "empty-set-expr";
			return emptyST;
		}
		String testSTName = "lookaheadTest";
		String testRangeSTName = "lookaheadRangeTest";
		String testSetSTName = "lookaheadSetTest";
		String varSTName = "lookaheadVarName";
		if ( !partOfDFA ) {
			testSTName = "isolatedLookaheadTest";
			testRangeSTName = "isolatedLookaheadRangeTest";
			testSetSTName = "isolatedLookaheadSetTest";
			varSTName = "isolatedLookaheadVarName";
		}
		ST setST = templates.getInstanceOf("setTest");
		// If the SetTest template exists, separate the ranges:
		// flatten the small ones into one list and make that a range,
		// and leave the others as they are.
		if ( templates.isDefined(testSetSTName) ) {
			// Flatten the IntervalSet into a list of integers.
			ST sST = templates.getInstanceOf(testSetSTName);
			Iterator iter = iset.getIntervals().iterator();
			int rangeNumber = 1;
			while (iter.hasNext()) {
				Interval I = iter.next();
				int a = I.a;
				int b = I.b;
				// Not flattening the large ranges helps us avoid making a
				// set that contains 90% of Unicode when we could just use
				// a simple range like (LA(1)>=123 && LA(1)<=65535).
				// This flattens all ranges of length 4 or less.
				if (b - a < 4) {
					for (int i = a; i <= b; i++) {
						sST.add("values", getTokenTypeAsTargetLabel(i));
						sST.add("valuesAsInt", Utils.integer(i));
					}
				} else {
					ST eST = templates.getInstanceOf(testRangeSTName);
					eST.add("lower", getTokenTypeAsTargetLabel(a));
					eST.add("lowerAsInt", Utils.integer(a));
					eST.add("upper", getTokenTypeAsTargetLabel(b));
					eST.add("upperAsInt", Utils.integer(b));
					eST.add("rangeNumber", Utils.integer(rangeNumber));
					eST.add("k", Utils.integer(k));
					setST.add("ranges", eST);
					rangeNumber++;
				}
			}
			sST.add("k", Utils.integer(k));
			setST.add("ranges", sST);
			return setST;
		}
		Iterator iter = iset.getIntervals().iterator();
		int rangeNumber = 1;
		while (iter.hasNext()) {
			Interval I = iter.next();
			int a = I.a;
			int b = I.b;
			ST eST;
			if ( a==b ) {
				eST = templates.getInstanceOf(testSTName);
				eST.add("atom", getTokenTypeAsTargetLabel(a));
				eST.add("atomAsInt", Utils.integer(a));
				//eST.add("k",Utils.integer(k));
			}
			else {
				eST = templates.getInstanceOf(testRangeSTName);
				eST.add("lower", getTokenTypeAsTargetLabel(a));
				eST.add("lowerAsInt", Utils.integer(a));
				eST.add("upper", getTokenTypeAsTargetLabel(b));
				eST.add("upperAsInt", Utils.integer(b));
				eST.add("rangeNumber", Utils.integer(rangeNumber));
			}
			eST.add("k", Utils.integer(k));
			setST.add("ranges", eST);
			rangeNumber++;
		}
		return setST;
	}

	// T O K E N  D E F I N I T I O N  G E N E R A T I O N

	/** Set attributes tokens and literals attributes in the incoming
	 *  code template.  This is not the token vocab interchange file, but
	 *  rather a list of token type ID needed by the recognizer.
	 */
	protected void genTokenTypeConstants(ST code) {
		// make constants for the token types
		for (String tokenID : grammar.getTokenIDs()) {
			int tokenType = grammar.getTokenType(tokenID);
			if ( tokenType==Label.EOF ||
				 tokenType>=Label.MIN_TOKEN_TYPE )
			{
				// don't do FAUX labels 'cept EOF
				code.addAggr("tokens.{name,type}", tokenID, Utils.integer(tokenType));
			}
		}
	}

	/** Generate a token names table that maps token type to a printable
	 *  name: either the label like INT or the literal like "begin".
	 */
	protected void genTokenTypeNames(ST code) {
		for (int t=Label.MIN_TOKEN_TYPE; t<=grammar.getMaxTokenType(); t++) {
			String tokenName = grammar.getTokenDisplayName(t);
			if ( tokenName!=null ) {
				tokenName=target.getTargetStringLiteralFromString(tokenName, true);
				code.add("tokenNames", tokenName);
			}
		}
	}

	/** Get a meaningful name for a token type useful during code generation.
	 *  Literals without associated names are converted to the string equivalent
	 *  of their integer values. Used to generate x==ID and x==34 type comparisons
	 *  etc...  Essentially we are looking for the most obvious way to refer
	 *  to a token type in the generated code.  If in the lexer, return the
	 *  char literal translated to the target language.  For example, ttype=10
	 *  will yield '\n' from the getTokenDisplayName method.  That must
	 *  be converted to the target languages literals.  For most C-derived
	 *  languages no translation is needed.
	 */
	public String getTokenTypeAsTargetLabel(int ttype) {
		if ( grammar.type==Grammar.LEXER ) {
			String name = grammar.getTokenDisplayName(ttype);
			return target.getTargetCharLiteralFromANTLRCharLiteral(this,name);
		}
		return target.getTokenTypeAsTargetLabel(this,ttype);
	}

	/** Generate a token vocab file with all the token names/types.  For example:
	 *  ID=7
	 *  FOR=8
	 *  'for'=8
	 *
	 *  This is independent of the target language; used by antlr internally
	 */
	protected ST genTokenVocabOutput() {
		ST vocabFileST = new ST(vocabFilePattern);
		vocabFileST.add("literals",(Object)null); // "define" literals arg
		vocabFileST.add("tokens",(Object)null);
		vocabFileST.impl.name = "vocab-file";
		// make constants for the token names
		for (String tokenID : grammar.getTokenIDs()) {
			int tokenType = grammar.getTokenType(tokenID);
			if ( tokenType>=Label.MIN_TOKEN_TYPE ) {
				vocabFileST.addAggr("tokens.{name,type}", tokenID, Utils.integer(tokenType));
			}
		}

		// now dump the strings
		for (String literal : grammar.getStringLiterals()) {
			int tokenType = grammar.getTokenType(literal);
			if ( tokenType>=Label.MIN_TOKEN_TYPE ) {
				vocabFileST.addAggr("tokens.{name,type}", literal, Utils.integer(tokenType));
			}
		}

		return vocabFileST;
	}

	public List translateAction(String ruleName,
								GrammarAST actionTree)
	{
		if ( actionTree.getType()==ANTLRParser.ARG_ACTION ) {
			return translateArgAction(ruleName, actionTree);
		}
		ActionTranslator translator = new ActionTranslator(this,ruleName,actionTree);
		List chunks = translator.translateToChunks();
		chunks = target.postProcessAction(chunks, actionTree.token);
		return chunks;
	}

	/** Translate an action like [3,"foo",a[3]] and return a List of the
	 *  translated actions.  Because actions are themselves translated to a list
	 *  of chunks, must cat together into a ST>.  Don't translate
	 *  to strings early as we need to eval templates in context.
	 */
	public List translateArgAction(String ruleName,
										   GrammarAST actionTree)
	{
		String actionText = actionTree.token.getText();
		List args = getListOfArgumentsFromAction(actionText,',');
		List translatedArgs = new ArrayList();
		for (String arg : args) {
			if ( arg!=null ) {
				Token actionToken =
					new CommonToken(ANTLRParser.ACTION,arg);
				ActionTranslator translator =
					new ActionTranslator(this,ruleName,
											  actionToken,
											  actionTree.outerAltNum);
				List chunks = translator.translateToChunks();
				chunks = target.postProcessAction(chunks, actionToken);
				ST catST = new ST(templates, "");
				catST.add("chunks", chunks);
				translatedArgs.add(catST);
			}
		}
		if ( translatedArgs.isEmpty() ) {
			return null;
		}
		return translatedArgs;
	}

	public static List getListOfArgumentsFromAction(String actionText,
															int separatorChar)
	{
		List args = new ArrayList();
		getListOfArgumentsFromAction(actionText, 0, -1, separatorChar, args);
		return args;
	}

	/** Given an arg action like
	 *
	 *  [x, (*a).foo(21,33), 3.2+1, '\n',
	 *  "a,oo\nick", {bl, "fdkj"eck}, ["cat\n,", x, 43]]
	 *
	 *  convert to a list of arguments.  Allow nested square brackets etc...
	 *  Set separatorChar to ';' or ',' or whatever you want.
	 */
	public static int getListOfArgumentsFromAction(String actionText,
												   int start,
												   int targetChar,
												   int separatorChar,
												   List args)
	{
		if ( actionText==null ) {
			return -1;
		}
		actionText = actionText.replaceAll("//.*\n", "");
		int n = actionText.length();
		//System.out.println("actionText@"+start+"->"+(char)targetChar+"="+actionText.substring(start,n));
		int p = start;
		int last = p;
		while ( p',p+1)>=p ) {
						// do we see a matching '>' ahead?  if so, hope it's a generic
						// and not less followed by expr with greater than
						p = getListOfArgumentsFromAction(actionText,p+1,'>',separatorChar,args);
					}
					else {
						p++; // treat as normal char
					}
					break;
				case '[' :
					p = getListOfArgumentsFromAction(actionText,p+1,']',separatorChar,args);
					break;
				default :
					if ( c==separatorChar && targetChar==-1 ) {
						String arg = actionText.substring(last, p);
						//System.out.println("arg="+arg);
						args.add(arg.trim());
						last = p+1;
					}
					p++;
					break;
			}
		}
		if ( targetChar==-1 && p<=n ) {
			String arg = actionText.substring(last, p).trim();
			//System.out.println("arg="+arg);
			if ( arg.length()>0 ) {
				args.add(arg.trim());
			}
		}
		p++;
		return p;
	}

	/** Given a template constructor action like %foo(a={...}) in
	 *  an action, translate it to the appropriate template constructor
	 *  from the templateLib. This translates a *piece* of the action.
	 */
	public ST translateTemplateConstructor(String ruleName,
													   int outerAltNum,
													   Token actionToken,
													   String templateActionText)
	{
		// first, parse with antlr.g
		//System.out.println("translate template: "+templateActionText);
		ANTLRLexer lexer = new ANTLRLexer(new ANTLRStringStream(templateActionText));
		lexer.setFileName(grammar.getFileName());
		ANTLRParser parser = ANTLRParser.createParser(new CommonTokenStream(lexer));
		parser.setFileName(grammar.getFileName());
		ANTLRParser.rewrite_template_return parseResult = null;
		try {
			parseResult = parser.rewrite_template();
		}
		catch (RecognitionException re) {
			ErrorManager.grammarError(ErrorManager.MSG_INVALID_TEMPLATE_ACTION,
										  grammar,
										  actionToken,
										  templateActionText);
		}
		catch (Exception tse) {
			ErrorManager.internalError("can't parse template action",tse);
		}
		GrammarAST rewriteTree = parseResult.getTree();

		// then translate via codegen.g
		CodeGenTreeWalker gen = new CodeGenTreeWalker(new CommonTreeNodeStream(rewriteTree));
		gen.init(grammar);
		gen.setCurrentRuleName(ruleName);
		gen.setOuterAltNum(outerAltNum);
		ST st = null;
		try {
			st = gen.rewrite_template();
		}
		catch (RecognitionException re) {
			ErrorManager.error(ErrorManager.MSG_BAD_AST_STRUCTURE,
							   re);
		}
		return st;
	}


	public void issueInvalidScopeError(String x,
									   String y,
									   Rule enclosingRule,
									   Token actionToken,
									   int outerAltNum)
	{
		//System.out.println("error $"+x+"::"+y);
		Rule r = grammar.getRule(x);
		AttributeScope scope = grammar.getGlobalScope(x);
		if ( scope==null ) {
			if ( r!=null ) {
				scope = r.ruleScope; // if not global, might be rule scope
			}
		}
		if ( scope==null ) {
			ErrorManager.grammarError(ErrorManager.MSG_UNKNOWN_DYNAMIC_SCOPE,
										  grammar,
										  actionToken,
										  x);
		}
		else if ( scope.getAttribute(y)==null ) {
			ErrorManager.grammarError(ErrorManager.MSG_UNKNOWN_DYNAMIC_SCOPE_ATTRIBUTE,
										  grammar,
										  actionToken,
										  x,
										  y);
		}
	}

	public void issueInvalidAttributeError(String x,
										   String y,
										   Rule enclosingRule,
										   Token actionToken,
										   int outerAltNum)
	{
		//System.out.println("error $"+x+"."+y);
		if ( enclosingRule==null ) {
			// action not in a rule
			ErrorManager.grammarError(ErrorManager.MSG_ATTRIBUTE_REF_NOT_IN_RULE,
										  grammar,
										  actionToken,
										  x,
										  y);
			return;
		}

		// action is in a rule
		Grammar.LabelElementPair label = enclosingRule.getRuleLabel(x);

		if ( label!=null || enclosingRule.getRuleRefsInAlt(x, outerAltNum)!=null ) {
			// $rulelabel.attr or $ruleref.attr; must be unknown attr
			String refdRuleName = x;
			if ( label!=null ) {
				refdRuleName = enclosingRule.getRuleLabel(x).referencedRuleName;
			}
			Rule refdRule = grammar.getRule(refdRuleName);
			AttributeScope scope = refdRule.getAttributeScope(y);
			if ( scope==null ) {
				ErrorManager.grammarError(ErrorManager.MSG_UNKNOWN_RULE_ATTRIBUTE,
										  grammar,
										  actionToken,
										  refdRuleName,
										  y);
			}
			else if ( scope.isParameterScope ) {
				ErrorManager.grammarError(ErrorManager.MSG_INVALID_RULE_PARAMETER_REF,
										  grammar,
										  actionToken,
										  refdRuleName,
										  y);
			}
			else if ( scope.isDynamicRuleScope ) {
				ErrorManager.grammarError(ErrorManager.MSG_INVALID_RULE_SCOPE_ATTRIBUTE_REF,
										  grammar,
										  actionToken,
										  refdRuleName,
										  y);
			}
		}

	}

	public void issueInvalidAttributeError(String x,
										   Rule enclosingRule,
										   Token actionToken,
										   int outerAltNum)
	{
		//System.out.println("error $"+x);
		if ( enclosingRule==null ) {
			// action not in a rule
			ErrorManager.grammarError(ErrorManager.MSG_ATTRIBUTE_REF_NOT_IN_RULE,
										  grammar,
										  actionToken,
										  x);
			return;
		}

		// action is in a rule
		Grammar.LabelElementPair label = enclosingRule.getRuleLabel(x);
		AttributeScope scope = enclosingRule.getAttributeScope(x);

		if ( label!=null ||
			 enclosingRule.getRuleRefsInAlt(x, outerAltNum)!=null ||
			 enclosingRule.name.equals(x) )
		{
			ErrorManager.grammarError(ErrorManager.MSG_ISOLATED_RULE_SCOPE,
										  grammar,
										  actionToken,
										  x);
		}
		else if ( scope!=null && scope.isDynamicRuleScope ) {
			ErrorManager.grammarError(ErrorManager.MSG_ISOLATED_RULE_ATTRIBUTE,
										  grammar,
										  actionToken,
										  x);
		}
		else {
			ErrorManager.grammarError(ErrorManager.MSG_UNKNOWN_SIMPLE_ATTRIBUTE,
									  grammar,
									  actionToken,
									  x);
		}
	}

	// M I S C

	public STGroup getTemplates() {
		return templates;
	}

	public STGroup getBaseTemplates() {
		return baseTemplates;
	}

	public void setDebug(boolean debug) {
		this.debug = debug;
	}

	public void setTrace(boolean trace) {
		this.trace = trace;
	}

	public void setProfile(boolean profile) {
		this.profile = profile;
		if ( profile ) {
			setDebug(true); // requires debug events
		}
	}

	public ST getRecognizerST() {
		return outputFileST;
	}

	/** Generate TParser.java and TLexer.java from T.g if combined, else
	 *  just use T.java as output regardless of type.
	 */
	public String getRecognizerFileName(String name, int type) {
		ST extST = templates.getInstanceOf("codeFileExtension");
		String recognizerName = grammar.getRecognizerName();
		return recognizerName+extST.render();
		/*
		String suffix = "";
		if ( type==Grammar.COMBINED ||
			 (type==Grammar.LEXER && !grammar.implicitLexer) )
		{
			suffix = Grammar.grammarTypeToFileNameSuffix[type];
		}
		return name+suffix+extST.toString();
		*/
	}

	/** What is the name of the vocab file generated for this grammar?
	 *  Returns null if no .tokens file should be generated.
	 */
	public String getVocabFileName() {
		if ( grammar.isBuiltFromString() ) {
			return null;
		}
		return grammar.name+VOCAB_FILE_EXTENSION;
	}

	public void write(ST code, String fileName) throws IOException {
		//long start = System.currentTimeMillis();
		Writer w = tool.getOutputFile(grammar, fileName);
		// Write the output to a StringWriter
		STWriter wr = new AutoIndentWriter(w);
		wr.setLineWidth(lineWidth);
		code.write(wr);
		w.close();
		//long stop = System.currentTimeMillis();
		//System.out.println("render time for "+fileName+": "+(int)(stop-start)+"ms");
	}

	/** You can generate a switch rather than if-then-else for a DFA state
	 *  if there are no semantic predicates and the number of edge label
	 *  values is small enough; e.g., don't generate a switch for a state
	 *  containing an edge label such as 20..52330 (the resulting byte codes
	 *  would overflow the method 65k limit probably).
	 */
	protected boolean canGenerateSwitch(DFAState s) {
		if ( !GENERATE_SWITCHES_WHEN_POSSIBLE ) {
			return false;
		}
		int size = 0;
		for (int i = 0; i < s.getNumberOfTransitions(); i++) {
			Transition edge = s.transition(i);
			if ( edge.label.isSemanticPredicate() ) {
				return false;
			}
			// can't do a switch if the edges are going to require predicates
			if ( edge.label.getAtom()==Label.EOT ) {
				int EOTPredicts = ((DFAState)edge.target).getUniquelyPredictedAlt();
				if ( EOTPredicts==NFA.INVALID_ALT_NUMBER ) {
					// EOT target has to be a predicate then; no unique alt
					return false;
				}
			}
			// if target is a state with gated preds, we need to use preds on
			// this edge then to reach it.
			if ( ((DFAState)edge.target).getGatedPredicatesInNFAConfigurations()!=null ) {
				return false;
			}
			size += edge.label.getSet().size();
		}
		if ( s.getNumberOfTransitions()MAX_SWITCH_CASE_LABELS ) {
			return false;
		}
		return true;
	}

	/** Create a label to track a token / rule reference's result.
	 *  Technically, this is a place where I break model-view separation
	 *  as I am creating a variable name that could be invalid in a
	 *  target language, however, label ::= <ID><INT> is probably ok in
	 *  all languages we care about.
	 */
	public String createUniqueLabel(String name) {
		return new StringBuffer()
			.append(name).append(uniqueLabelNumber++).toString();
	}
}
    
    
    
    

    




    
    
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