/*
 * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

package org.antlr.v4.codegen;

import org.antlr.v4.Tool;
import org.antlr.v4.codegen.model.RuleFunction;
import org.antlr.v4.codegen.model.SerializedATN;
import org.antlr.v4.misc.CharSupport;
import org.antlr.v4.misc.Utils;
import org.antlr.v4.parse.ANTLRParser;
import org.antlr.v4.runtime.RuntimeMetaData;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.tool.ErrorType;
import org.antlr.v4.tool.Grammar;
import org.antlr.v4.tool.Rule;
import org.antlr.v4.tool.ast.GrammarAST;
import org.stringtemplate.v4.NumberRenderer;
import org.stringtemplate.v4.ST;
import org.stringtemplate.v4.STErrorListener;
import org.stringtemplate.v4.STGroup;
import org.stringtemplate.v4.STGroupFile;
import org.stringtemplate.v4.StringRenderer;
import org.stringtemplate.v4.misc.STMessage;

import java.net.URL;

/** */
public abstract class Target {
	
For pure strings of Java 16-bit Unicode char, how can we display
 it in the target language as a literal.  Useful for dumping
 predicates and such that may refer to chars that need to be escaped
 when represented as strings.  Also, templates need to be escaped so
 that the target language can hold them as a string.
 
 I have defined (via the constructor) the set of typical escapes, but your Target subclass is free to alter the translated chars or add more definitions. This is non-static so each target can have a different set in memory at same time. /** For pure strings of Java 16-bit Unicode char, how can we display
	 *  it in the target language as a literal.  Useful for dumping
	 *  predicates and such that may refer to chars that need to be escaped
	 *  when represented as strings.  Also, templates need to be escaped so
	 *  that the target language can hold them as a string.
	 *  <p>
	 *  I have defined (via the constructor) the set of typical escapes,
	 *  but your {@link Target} subclass is free to alter the translated chars
	 *  or add more definitions.  This is non-static so each target can have
	 *  a different set in memory at same time.
	 */
	protected String[] targetCharValueEscape = new String[255];

	protected final CodeGenerator gen;
	private final String language;
	private STGroup templates;

	protected Target(CodeGenerator gen, String language) {
		targetCharValueEscape['\n'] = "\\n";
		targetCharValueEscape['\r'] = "\\r";
		targetCharValueEscape['\t'] = "\\t";
		targetCharValueEscape['\b'] = "\\b";
		targetCharValueEscape['\f'] = "\\f";
		targetCharValueEscape['\\'] = "\\\\";
		targetCharValueEscape['\''] = "\\'";
		targetCharValueEscape['"'] = "\\\"";
		this.gen = gen;
		this.language = language;
	}

	public CodeGenerator getCodeGenerator() {
		return gen;
	}

	public String getLanguage() {
		return language;
	}

	
ANTLR tool should check output templates / target are compatible with tool code generation.
 For now, a simple string match used on x.y of x.y.z scheme. We use a method to avoid mismatches
 between a template called VERSION. This value is checked against Tool.VERSION during load of templates.
 This additional method forces all targets 4.3 and beyond to add this method.
Since:
4.3/** ANTLR tool should check output templates / target are compatible with tool code generation.
	 *  For now, a simple string match used on x.y of x.y.z scheme. We use a method to avoid mismatches
	 *  between a template called VERSION. This value is checked against Tool.VERSION during load of templates.
	 *
	 *  This additional method forces all targets 4.3 and beyond to add this method.
	 *
	 * @since 4.3
	 */
	public abstract String getVersion();

	public STGroup getTemplates() {
		if (templates == null) {
			String version = getVersion();
			if ( version==null ||
				 !RuntimeMetaData.getMajorMinorVersion(version).equals(RuntimeMetaData.getMajorMinorVersion(Tool.VERSION)))
			{
				gen.tool.errMgr.toolError(ErrorType.INCOMPATIBLE_TOOL_AND_TEMPLATES, version, Tool.VERSION, language);
			}
			templates = loadTemplates();
		}

		return templates;
	}

	protected void genFile(Grammar g, ST outputFileST, String fileName)
	{
		getCodeGenerator().write(outputFileST, fileName);
	}

	
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.
/** 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.
	 */
	public String getTokenTypeAsTargetLabel(Grammar g, int ttype) {
		String name = g.getTokenName(ttype);
		// If name is not valid, return the token type instead
		if ( Grammar.INVALID_TOKEN_NAME.equals(name) ) {
			return String.valueOf(ttype);
		}

		return name;
	}

	public String[] getTokenTypesAsTargetLabels(Grammar g, int[] ttypes) {
		String[] labels = new String[ttypes.length];
		for (int i=0; i<ttypes.length; i++) {
			labels[i] = getTokenTypeAsTargetLabel(g, ttypes[i]);
		}
		return labels;
	}

	
Given a random string of Java unicode chars, return a new string with
 optionally appropriate quote characters for target language and possibly
 with some escaped characters.  For example, if the incoming string has
 actual newline characters, the output of this method would convert them
 to the two char sequence \n for Java, C, C++, ...  The new string has
 double-quotes around it as well.  Example String in memory:
    a"[newlinechar]b'c[carriagereturnchar]d[tab]e\f
 would be converted to the valid Java s:
    "a\"\nb'c\rd\te\\f"
 or
    a\"\nb'c\rd\te\\f
 depending on the quoted arg.
/** Given a random string of Java unicode chars, return a new string with
	 *  optionally appropriate quote characters for target language and possibly
	 *  with some escaped characters.  For example, if the incoming string has
	 *  actual newline characters, the output of this method would convert them
	 *  to the two char sequence \n for Java, C, C++, ...  The new string has
	 *  double-quotes around it as well.  Example String in memory:
	 *
	 *     a"[newlinechar]b'c[carriagereturnchar]d[tab]e\f
	 *
	 *  would be converted to the valid Java s:
	 *
	 *     "a\"\nb'c\rd\te\\f"
	 *
	 *  or
	 *
	 *     a\"\nb'c\rd\te\\f
	 *
	 *  depending on the quoted arg.
	 */
	public String getTargetStringLiteralFromString(String s, boolean quoted) {
		if ( s==null ) {
			return null;
		}

		StringBuilder buf = new StringBuilder();
		if ( quoted ) {
			buf.append('"');
		}
		for (int i=0; i<s.length(); ) {
			int c = s.codePointAt(i);
			if ( c!='\'' && // don't escape single quotes in strings for java
				 c<targetCharValueEscape.length &&
				 targetCharValueEscape[c]!=null )
			{
				buf.append(targetCharValueEscape[c]);
			}
			else if (shouldUseUnicodeEscapeForCodePointInDoubleQuotedString(c)) {
				appendUnicodeEscapedCodePoint(i, buf);
			}
			else
			{
				buf.appendCodePoint(c);
			}
			i += Character.charCount(c);
		}
		if ( quoted ) {
			buf.append('"');
		}
		return buf.toString();
	}

	
Escape the Unicode code point appropriately for this language and append the escaped value to sb. /**
	 * Escape the Unicode code point appropriately for this language
	 * and append the escaped value to {@code sb}.
	 */
	abstract protected void appendUnicodeEscapedCodePoint(int codePoint, StringBuilder sb);

	public String getTargetStringLiteralFromString(String s) {
		return getTargetStringLiteralFromString(s, true);
	}

	
Convert from an ANTLR string literal found in a grammar file to an
equivalent string literal in the target language.

 For Java, this is the translation 'a\n"' → "a\n\"". Expect single quotes around the incoming literal. Just flip the quotes and replace double quotes with \". 
 Note that we have decided to allow people to use '\"' without penalty, so we must build the target string in a loop as String.replace cannot handle both \" and " without a lot of messing around. 
/**
	 * <p>Convert from an ANTLR string literal found in a grammar file to an
	 * equivalent string literal in the target language.
	 *</p>
	 * <p>
	 * For Java, this is the translation {@code 'a\n"'} &rarr; {@code "a\n\""}.
	 * Expect single quotes around the incoming literal. Just flip the quotes
	 * and replace double quotes with {@code \"}.
	 * </p>
	 * <p>
	 * Note that we have decided to allow people to use '\"' without penalty, so
	 * we must build the target string in a loop as {@link String#replace}
	 * cannot handle both {@code \"} and {@code "} without a lot of messing
	 * around.
	 * </p>
	 */
	public String getTargetStringLiteralFromANTLRStringLiteral(
		CodeGenerator generator,
		String literal,
		boolean addQuotes)
	{
		StringBuilder sb = new StringBuilder();
		String is = literal;

		if ( addQuotes ) sb.append('"');

		for (int i = 1; i < is.length() -1; ) {
			int codePoint = is.codePointAt(i);
			int toAdvance = Character.charCount(codePoint);
			if  (codePoint == '\\') {
				// Anything escaped is what it is! We assume that
				// people know how to escape characters correctly. However
				// we catch anything that does not need an escape in Java (which
				// is what the default implementation is dealing with and remove
				// the escape. The C target does this for instance.
				//
				int escapedCodePoint = is.codePointAt(i+toAdvance);
				toAdvance++;
				switch (escapedCodePoint) {
					// Pass through any escapes that Java also needs
					//
					case    'n':
					case    'r':
					case    't':
					case    'b':
					case    'f':
					case    '\\':
						// Pass the escape through
						sb.append('\\');
						sb.appendCodePoint(escapedCodePoint);
						break;

					case    'u':    // Either unnnn or u{nnnnnn}
						if (is.charAt(i+toAdvance) == '{') {
							while (is.charAt(i+toAdvance) != '}') {
								toAdvance++;
							}
							toAdvance++;
						}
						else {
							toAdvance += 4;
						}
						if ( i+toAdvance <= is.length() ) { // we might have an invalid \\uAB or something
							String fullEscape = is.substring(i, i+toAdvance);
							appendUnicodeEscapedCodePoint(
								CharSupport.getCharValueFromCharInGrammarLiteral(fullEscape),
								sb);
						}
						break;
					default:
						if (shouldUseUnicodeEscapeForCodePointInDoubleQuotedString(escapedCodePoint)) {
							appendUnicodeEscapedCodePoint(escapedCodePoint, sb);
						}
						else {
							sb.appendCodePoint(escapedCodePoint);
						}
						break;
				}
			}
			else {
				if (codePoint == 0x22) {
					// ANTLR doesn't escape " in literal strings,
					// but every other language needs to do so.
					sb.append("\\\"");
				}
				else if (shouldUseUnicodeEscapeForCodePointInDoubleQuotedString(codePoint)) {
					appendUnicodeEscapedCodePoint(codePoint, sb);
				}
				else {
					sb.appendCodePoint(codePoint);
				}
			}
			i += toAdvance;
		}

		if ( addQuotes ) sb.append('"');

		return sb.toString();
	}

	private static boolean shouldUseUnicodeEscapeForCodePointInDoubleQuotedString(int codePoint) {
		// We don't want anyone passing 0x0A (newline) or 0x22
		// (double-quote) here because Java treats \\u000A as
		// a literal newline and \\u0022 as a literal
		// double-quote, so Unicode escaping doesn't help.
		assert codePoint != 0x0A && codePoint != 0x22;

		return
			codePoint < 0x20  || // control characters up to but not including space
			codePoint == 0x5C || // backslash
			codePoint >= 0x7F;   // DEL and beyond (keeps source code 7-bit US-ASCII)
	}

	
Assume 16-bit char /** Assume 16-bit char */
	public String encodeIntAsCharEscape(int v) {
		if (v < Character.MIN_VALUE || v > Character.MAX_VALUE) {
			throw new IllegalArgumentException(String.format("Cannot encode the specified value: %d", v));
		}

		if (v >= 0 && v < targetCharValueEscape.length && targetCharValueEscape[v] != null) {
			return targetCharValueEscape[v];
		}

		if (v >= 0x20 && v < 127 && (!Character.isDigit(v) || v == '8' || v == '9')) {
			return String.valueOf((char)v);
		}

		if ( v>=0 && v<=127 ) {
			String oct = Integer.toOctalString(v);
			return "\\"+ oct;
		}

		String hex = Integer.toHexString(v|0x10000).substring(1,5);
		return "\\u"+hex;
	}

	public String getLoopLabel(GrammarAST ast) {
		return "loop"+ ast.token.getTokenIndex();
	}

	public String getLoopCounter(GrammarAST ast) {
		return "cnt"+ ast.token.getTokenIndex();
	}

	public String getListLabel(String label) {
		ST st = getTemplates().getInstanceOf("ListLabelName");
		st.add("label", label);
		return st.render();
	}

	public String getRuleFunctionContextStructName(Rule r) {
		if ( r.g.isLexer() ) {
			return getTemplates().getInstanceOf("LexerRuleContext").render();
		}
		return Utils.capitalize(r.name)+getTemplates().getInstanceOf("RuleContextNameSuffix").render();
	}

	public String getAltLabelContextStructName(String label) {
		return Utils.capitalize(label)+getTemplates().getInstanceOf("RuleContextNameSuffix").render();
	}

	
If we know which actual function, we can provide the actual ctx type.
 This will contain implicit labels etc...  From outside, though, we
 see only ParserRuleContext unless there are externally visible stuff
 like args, locals, explicit labels, etc...
/** If we know which actual function, we can provide the actual ctx type.
	 *  This will contain implicit labels etc...  From outside, though, we
	 *  see only ParserRuleContext unless there are externally visible stuff
	 *  like args, locals, explicit labels, etc...
	 */
	public String getRuleFunctionContextStructName(RuleFunction function) {
		Rule r = function.rule;
		if ( r.g.isLexer() ) {
			return getTemplates().getInstanceOf("LexerRuleContext").render();
		}
		return Utils.capitalize(r.name)+getTemplates().getInstanceOf("RuleContextNameSuffix").render();
	}

	// should be same for all refs to same token like ctx.ID within single rule function
	// for literals like 'while', we gen _s<ttype>
	public String getImplicitTokenLabel(String tokenName) {
		ST st = getTemplates().getInstanceOf("ImplicitTokenLabel");
		int ttype = getCodeGenerator().g.getTokenType(tokenName);
		if ( tokenName.startsWith("'") ) {
			return "s"+ttype;
		}
		String text = getTokenTypeAsTargetLabel(getCodeGenerator().g, ttype);
		st.add("tokenName", text);
		return st.render();
	}

	// x=(A|B)
	public String getImplicitSetLabel(String id) {
		ST st = getTemplates().getInstanceOf("ImplicitSetLabel");
		st.add("id", id);
		return st.render();
	}

	public String getImplicitRuleLabel(String ruleName) {
		ST st = getTemplates().getInstanceOf("ImplicitRuleLabel");
		st.add("ruleName", ruleName);
		return st.render();
	}

	public String getElementListName(String name) {
		ST st = getTemplates().getInstanceOf("ElementListName");
		st.add("elemName", getElementName(name));
		return st.render();
	}

	public String getElementName(String name) {
		if (".".equals(name)) {
			return "_wild";
		}

		if ( getCodeGenerator().g.getRule(name)!=null ) return name;
		int ttype = getCodeGenerator().g.getTokenType(name);
		if ( ttype==Token.INVALID_TYPE ) return name;
		return getTokenTypeAsTargetLabel(getCodeGenerator().g, ttype);
	}

	
Generate TParser.java and TLexer.java from T.g4 if combined, else
 just use T.java as output regardless of type.
/** Generate TParser.java and TLexer.java from T.g4 if combined, else
	 *  just use T.java as output regardless of type.
	 */
	public String getRecognizerFileName(boolean header) {
		ST extST = getTemplates().getInstanceOf("codeFileExtension");
		String recognizerName = gen.g.getRecognizerName();
		return recognizerName+extST.render();
	}

	
A given grammar T, return the listener name such as
 TListener.java, if we're using the Java target.
/** A given grammar T, return the listener name such as
	 *  TListener.java, if we're using the Java target.
 	 */
	public String getListenerFileName(boolean header) {
		assert gen.g.name != null;
		ST extST = getTemplates().getInstanceOf("codeFileExtension");
		String listenerName = gen.g.name + "Listener";
		return listenerName+extST.render();
	}

	
A given grammar T, return the visitor name such as
 TVisitor.java, if we're using the Java target.
/** A given grammar T, return the visitor name such as
	 *  TVisitor.java, if we're using the Java target.
 	 */
	public String getVisitorFileName(boolean header) {
		assert gen.g.name != null;
		ST extST = getTemplates().getInstanceOf("codeFileExtension");
		String listenerName = gen.g.name + "Visitor";
		return listenerName+extST.render();
	}

	
A given grammar T, return a blank listener implementation
 such as TBaseListener.java, if we're using the Java target.
/** A given grammar T, return a blank listener implementation
	 *  such as TBaseListener.java, if we're using the Java target.
 	 */
	public String getBaseListenerFileName(boolean header) {
		assert gen.g.name != null;
		ST extST = getTemplates().getInstanceOf("codeFileExtension");
		String listenerName = gen.g.name + "BaseListener";
		return listenerName+extST.render();
	}

	
A given grammar T, return a blank listener implementation
 such as TBaseListener.java, if we're using the Java target.
/** A given grammar T, return a blank listener implementation
	 *  such as TBaseListener.java, if we're using the Java target.
 	 */
	public String getBaseVisitorFileName(boolean header) {
		assert gen.g.name != null;
		ST extST = getTemplates().getInstanceOf("codeFileExtension");
		String listenerName = gen.g.name + "BaseVisitor";
		return listenerName+extST.render();
	}

	
Gets the maximum number of 16-bit unsigned integers that can be encoded
in a single segment of the serialized ATN.
See Also:
getSegments.getSegments
Returns:
the serialized ATN segment limit/**
	 * Gets the maximum number of 16-bit unsigned integers that can be encoded
	 * in a single segment of the serialized ATN.
	 *
	 * @see SerializedATN#getSegments
	 *
	 * @return the serialized ATN segment limit
	 */
	public int getSerializedATNSegmentLimit() {
		return Integer.MAX_VALUE;
	}

	
How many bits should be used to do inline token type tests? Java assumes
 a 64-bit word for bitsets.  Must be a valid wordsize for your target like
 8, 16, 32, 64, etc...
 @since 4.5
/** How many bits should be used to do inline token type tests? Java assumes
	 *  a 64-bit word for bitsets.  Must be a valid wordsize for your target like
	 *  8, 16, 32, 64, etc...
	 *
	 *  @since 4.5
	 */
	public int getInlineTestSetWordSize() { return 64; }

	public boolean grammarSymbolCausesIssueInGeneratedCode(GrammarAST idNode) {
		switch (idNode.getParent().getType()) {
			case ANTLRParser.ASSIGN:
				switch (idNode.getParent().getParent().getType()) {
					case ANTLRParser.ELEMENT_OPTIONS:
					case ANTLRParser.OPTIONS:
						return false;

					default:
						break;
				}

				break;

			case ANTLRParser.AT:
			case ANTLRParser.ELEMENT_OPTIONS:
				return false;

			case ANTLRParser.LEXER_ACTION_CALL:
				if (idNode.getChildIndex() == 0) {
					// first child is the command name which is part of the ANTLR language
					return false;
				}

				// arguments to the command should be checked
				break;

			default:
				break;
		}

		return visibleGrammarSymbolCausesIssueInGeneratedCode(idNode);
	}

	protected abstract boolean visibleGrammarSymbolCausesIssueInGeneratedCode(GrammarAST idNode);

	public boolean templatesExist() {
		String groupFileName = CodeGenerator.TEMPLATE_ROOT + "/" + getLanguage() + "/" + getLanguage() + STGroup.GROUP_FILE_EXTENSION;
		STGroup result = null;
		try {
			result = new STGroupFile(groupFileName);
		}
		catch (IllegalArgumentException iae) {
			result = null;
		}
		return result!=null;
	}


	protected STGroup loadTemplates() {
		String groupFileName = CodeGenerator.TEMPLATE_ROOT + "/" + getLanguage() + "/" + getLanguage() + STGroup.GROUP_FILE_EXTENSION;
		STGroup result = null;
		try {
			result = new STGroupFile(groupFileName);
		}
		catch (IllegalArgumentException iae) {
			gen.tool.errMgr.toolError(ErrorType.MISSING_CODE_GEN_TEMPLATES,
						 iae,
						 language);
		}
		if ( result==null ) return null;
		result.registerRenderer(Integer.class, new NumberRenderer());
		result.registerRenderer(String.class, new StringRenderer());
		result.setListener(new STErrorListener() {
			@Override
			public void compileTimeError(STMessage msg) {
				reportError(msg);
			}

			@Override
			public void runTimeError(STMessage msg) {
				reportError(msg);
			}

			@Override
			public void IOError(STMessage msg) {
				reportError(msg);
			}

			@Override
			public void internalError(STMessage msg) {
				reportError(msg);
			}

			private void reportError(STMessage msg) {
				getCodeGenerator().tool.errMgr.toolError(ErrorType.STRING_TEMPLATE_WARNING, msg.cause, msg.toString());
			}
		});

		return result;
	}

	
Since:
4.3/**
	 * @since 4.3
	 */
	public boolean wantsBaseListener() {
		return true;
	}

	
Since:
4.3/**
	 * @since 4.3
	 */
	public boolean wantsBaseVisitor() {
		return true;
	}

	
Since:
4.3/**
	 * @since 4.3
	 */
	public boolean supportsOverloadedMethods() {
		return true;
	}

	
Since:
4.6/** @since 4.6 */
	public boolean needsHeader() { return false; }; // Override in targets that need header files.
}