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Diffstat (limited to 'src/main/java/com/google/escapevelocity/EvaluationContext.java')
-rw-r--r-- | src/main/java/com/google/escapevelocity/EvaluationContext.java | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/src/main/java/com/google/escapevelocity/EvaluationContext.java b/src/main/java/com/google/escapevelocity/EvaluationContext.java new file mode 100644 index 0000000..d40b717 --- /dev/null +++ b/src/main/java/com/google/escapevelocity/EvaluationContext.java @@ -0,0 +1,85 @@ +/* + * Copyright (C) 2018 Google, Inc. + * + * 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.escapevelocity; + +import com.google.common.collect.ImmutableSet; +import java.lang.reflect.Method; +import java.util.Map; +import java.util.TreeMap; + +/** + * The context of a template evaluation. This consists of the template variables and the template + * macros. The template variables start with the values supplied by the evaluation call, and can + * be changed by {@code #set} directives and during the execution of {@code #foreach} and macro + * calls. The macros are extracted from the template during parsing and never change thereafter. + * + * @author emcmanus@google.com (Éamonn McManus) + */ +interface EvaluationContext { + Object getVar(String var); + + boolean varIsDefined(String var); + + /** + * Sets the given variable to the given value. + * + * @return a Runnable that will restore the variable to the value it had before. If the variable + * was undefined before this method was executed, the Runnable will make it undefined again. + * This allows us to restore the state of {@code $x} after {@code #foreach ($x in ...)}. + */ + Runnable setVar(final String var, Object value); + + /** See {@link MethodFinder#publicMethodsWithName}. */ + ImmutableSet<Method> publicMethodsWithName(Class<?> startClass, String name); + + class PlainEvaluationContext implements EvaluationContext { + private final Map<String, Object> vars; + private final MethodFinder methodFinder; + + PlainEvaluationContext(Map<String, ?> vars, MethodFinder methodFinder) { + this.vars = new TreeMap<>(vars); + this.methodFinder = methodFinder; + } + + @Override + public Object getVar(String var) { + return vars.get(var); + } + + @Override + public boolean varIsDefined(String var) { + return vars.containsKey(var); + } + + @Override + public Runnable setVar(final String var, Object value) { + Runnable undo; + if (vars.containsKey(var)) { + final Object oldValue = vars.get(var); + undo = () -> vars.put(var, oldValue); + } else { + undo = () -> vars.remove(var); + } + vars.put(var, value); + return undo; + } + + @Override + public ImmutableSet<Method> publicMethodsWithName(Class<?> startClass, String name) { + return methodFinder.publicMethodsWithName(startClass, name); + } + } +} |