| // Copyright 2014 The Bazel Authors. All rights reserved. |
| // |
| // 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.google.devtools.build.lib.query2.engine; |
| |
| import java.util.Collection; |
| import java.util.Set; |
| import java.util.regex.Pattern; |
| |
| /** |
| * A let expression. |
| * |
| * <pre>expr ::= LET WORD = expr IN expr</pre> |
| */ |
| class LetExpression extends QueryExpression { |
| |
| private static final String VAR_NAME_PATTERN = "[a-zA-Z_][a-zA-Z0-9_]*$"; |
| |
| // Variables names may be any legal identifier in the C programming language |
| private static final Pattern NAME_PATTERN = Pattern.compile("^" + VAR_NAME_PATTERN); |
| |
| // Variable references are prepended with the "$" character. |
| // A variable named "x" is referenced as "$x". |
| private static final Pattern REF_PATTERN = Pattern.compile("^\\$" + VAR_NAME_PATTERN); |
| |
| static boolean isValidVarReference(String varName) { |
| return REF_PATTERN.matcher(varName).matches(); |
| } |
| |
| static String getNameFromReference(String reference) { |
| return reference.substring(1); |
| } |
| |
| private final String varName; |
| private final QueryExpression varExpr; |
| private final QueryExpression bodyExpr; |
| |
| LetExpression(String varName, QueryExpression varExpr, QueryExpression bodyExpr) { |
| this.varName = varName; |
| this.varExpr = varExpr; |
| this.bodyExpr = bodyExpr; |
| } |
| |
| String getVarName() { |
| return varName; |
| } |
| |
| QueryExpression getVarExpr() { |
| return varExpr; |
| } |
| |
| QueryExpression getBodyExpr() { |
| return bodyExpr; |
| } |
| |
| @Override |
| protected <T> void evalImpl( |
| QueryEnvironment<T> env, VariableContext<T> context, Callback<T> callback) |
| throws QueryException, InterruptedException { |
| if (!NAME_PATTERN.matcher(varName).matches()) { |
| throw new QueryException(this, "invalid variable name '" + varName + "' in let expression"); |
| } |
| Set<T> varValue = QueryUtil.evalAll(env, context, varExpr); |
| VariableContext<T> bodyContext = VariableContext.with(context, varName, varValue); |
| env.eval(bodyExpr, bodyContext, callback); |
| } |
| |
| @Override |
| public void collectTargetPatterns(Collection<String> literals) { |
| varExpr.collectTargetPatterns(literals); |
| bodyExpr.collectTargetPatterns(literals); |
| } |
| |
| @Override |
| public QueryExpression getMapped(QueryExpressionMapper mapper) { |
| return mapper.map(this); |
| } |
| |
| @Override |
| public String toString() { |
| return "let " + varName + " = " + varExpr + " in " + bodyExpr; |
| } |
| } |