Java tutorial
/** * Copyright (c) 2012-2013 Edgar Espina * * This file is part of Handlebars.java. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.github.jknack.handlebars.internal; import static org.apache.commons.lang3.Validate.notEmpty; import org.antlr.v4.runtime.DefaultErrorStrategy; import org.antlr.v4.runtime.InputMismatchException; import org.antlr.v4.runtime.NoViableAltException; import org.antlr.v4.runtime.Parser; import org.antlr.v4.runtime.RecognitionException; import org.antlr.v4.runtime.Token; import org.antlr.v4.runtime.TokenStream; import org.antlr.v4.runtime.misc.IntervalSet; import org.apache.commons.lang3.StringUtils; import com.github.jknack.handlebars.HandlebarsException; import com.github.jknack.handlebars.internal.HbsParser.AmpvarContext; import com.github.jknack.handlebars.internal.HbsParser.BlockContext; import com.github.jknack.handlebars.internal.HbsParser.CommentContext; import com.github.jknack.handlebars.internal.HbsParser.DelimitersContext; import com.github.jknack.handlebars.internal.HbsParser.PartialContext; import com.github.jknack.handlebars.internal.HbsParser.TvarContext; import com.github.jknack.handlebars.internal.HbsParser.UnlessContext; import com.github.jknack.handlebars.internal.HbsParser.VarContext; /** * Fail in upon first error. * * @author edgar.espina * @since 0.10.0 */ class HbsErrorStrategy extends DefaultErrorStrategy { /** * Help to provide better error. * * @author edgar.espina * @since 0.10.0 */ private class ErrorStrategyVisitor extends HbsParserBaseVisitor<String> { /** * The start delimiter. */ private String startDelimiter; /** * The end delimiter. */ private String endDelimiter; /** * Creates a new {@link ErrorStrategyVisitor}. * * @param startDelimiter The start delimiter. * @param endDelimiter The end delimiter. */ public ErrorStrategyVisitor(final String startDelimiter, final String endDelimiter) { this.startDelimiter = notEmpty(startDelimiter, "The startDelimiter can't be empty/null."); this.endDelimiter = notEmpty(endDelimiter, "The end delimiter can't be empty/null."); } @Override public String visitVar(final VarContext ctx) { if (ctx.stop == null) { return endDelimiter; } return null; } @Override public String visitTvar(final TvarContext ctx) { if (ctx.stop == null) { return "}" + endDelimiter; } return null; } @Override public String visitAmpvar(final AmpvarContext ctx) { if (ctx.stop == null) { return endDelimiter; } return null; } @Override public String visitBlock(final BlockContext ctx) { if (ctx.stop == null) { return startDelimiter + "/"; } return null; } @Override public String visitUnless(final UnlessContext ctx) { if (ctx.stop == null) { return endDelimiter; } return null; } @Override public String visitPartial(final PartialContext ctx) { if (ctx.stop == null) { return endDelimiter; } return null; } @Override public String visitComment(final CommentContext ctx) { if (ctx.stop == null) { return endDelimiter; } return null; } @Override public String visitDelimiters(final DelimitersContext ctx) { if (ctx.stop == null) { return "=" + endDelimiter; } return null; } } @Override public void recover(final Parser recognizer, final RecognitionException e) { // always fail throw new HandlebarsException(e); } @Override public Token recoverInline(final Parser recognizer) { // always fail throw new InputMismatchException(recognizer); } @Override public void reportNoViableAlternative(final Parser recognizer, final NoViableAltException e) { HbsParser parser = (HbsParser) recognizer; TokenStream tokens = parser.getTokenStream(); HbsLexer lexer = (HbsLexer) tokens.getTokenSource(); String msg = new ErrorStrategyVisitor(lexer.start, lexer.end).visit(e.getCtx()); if (msg != null) { recognizer.notifyErrorListeners(e.getOffendingToken(), msg, e); } else { super.reportNoViableAlternative(recognizer, e); } } @Override public void reportMissingToken(final Parser recognizer) { if (errorRecoveryMode) { return; } Token offendingToken = recognizer.getCurrentToken(); IntervalSet expecting = getExpectedTokens(recognizer); String msg = expecting.toString(recognizer.getTokenNames()); recognizer.notifyErrorListeners(offendingToken, msg, null); } @Override public void reportInputMismatch(final Parser recognizer, final InputMismatchException e) { String[] displayNames = displayNames(recognizer); String msg = e.getExpectedTokens().toString(displayNames); recognizer.notifyErrorListeners(e.getOffendingToken(), msg, e); } /** * Translate the token's name to name that make more sense to the user. * * @param recognizer The lexer/parser. * @return User error messages. */ private String[] displayNames(final Parser recognizer) { HbsParser parser = (HbsParser) recognizer; TokenStream tokens = parser.getTokenStream(); HbsLexer lexer = (HbsLexer) tokens.getTokenSource(); String[] tokenNames = recognizer.getTokenNames(); String[] displayName = new String[tokenNames.length]; for (int i = 0; i < displayName.length; i++) { String[] parts = StringUtils.split(tokenNames[i], "_"); if (parts[0].equals("START")) { String suffix = ""; if (parts.length > 1) { if (parts[1].equals("COMMENT")) { suffix = "!"; } else if (parts[1].equals("AMP")) { suffix = "&"; } else if (parts[1].equals("T")) { suffix = "{"; } else if (parts[1].equals("BLOCK")) { suffix = "#"; } else if (parts[1].equals("DELIM")) { suffix = "="; } else if (parts[1].equals("PARTIAL")) { suffix = ">"; } } displayName[i] = lexer.start + suffix; } else if (parts[0].equals("END")) { String prefix = ""; if (parts.length > 1) { if (parts[1].equals("BLOCK")) { displayName[i] = lexer.start + "/"; } else if (parts[1].equals("DELIM")) { prefix = "="; displayName[i] = prefix + lexer.end; } else if (parts[1].equals("T")) { prefix = "}"; displayName[i] = prefix + lexer.end; } else { displayName[i] = prefix + lexer.end; } } else { displayName[i] = prefix + lexer.end; } } else if (parts[0].equals("UNLESS")) { displayName[i] = "^"; } else if (parts[0].equals("NL")) { displayName[i] = "\\n"; } else if (parts[0].equals("WS")) { displayName[i] = "space"; } else if (parts[0].equals("DOUBLE")) { displayName[i] = "string"; } else if (parts[0].equals("SINGLE")) { displayName[i] = "string"; } else if (parts[0].equals("QID")) { displayName[i] = "id"; } else { displayName[i] = tokenNames[i]; } displayName[i] = displayName[i].toLowerCase().replace("'", ""); } return displayName; } @Override public void sync(final Parser recognizer) { // never sync } }