Refactor Skylark Environment-s

Make Environment-s freezable: Introduce a class Mutability
as a revokable capability to mutate objects in an Environment.
For now, only Environment-s carry this capability.
Make sure that every Mutability is revoked in the same function that creates it,
so no Environment is left open for modification after being created and exported;
exceptions for tests, the shell and initialization contexts.

Unify Environment, SkylarkEnvironment and EvaluationContext into Environment.
Have a notion of Frame for the bindings + parent + mutability.
Replace the updateAndPropagate mechanism by a dynamicFrame.
Simplify ValidationEnvironment, that is now always deduced from the Environment.

--
MOS_MIGRATED_REVID=102363438

1 files changed, 0 insertions, 195 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java b/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java
deleted file mode 100644
index 6a24cb3cac..0000000000
--- a/src/main/java/com/google/devtools/build/lib/syntax/EvaluationContext.java
+++ /dev/null
@@ -1,195 +0,0 @@
-// Copyright 2015 Google Inc. 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.syntax;
-
-import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Joiner;
-import com.google.common.base.Preconditions;
-import com.google.devtools.build.lib.cmdline.PackageIdentifier;
-import com.google.devtools.build.lib.events.Event;
-import com.google.devtools.build.lib.events.EventHandler;
-import com.google.devtools.build.lib.events.EventKind;
-import com.google.devtools.build.lib.packages.CachingPackageLocator;
-import com.google.devtools.build.lib.syntax.Environment.NoSuchVariableException;
-import com.google.devtools.build.lib.vfs.Path;
-
-import java.util.List;
-
-import javax.annotation.Nullable;
-
-/**
- * Context for the evaluation of programs.
- */
-public final class EvaluationContext {
-
-  @Nullable private EventHandler eventHandler;
-  private Environment env;
-  @Nullable private ValidationEnvironment validationEnv;
-  private boolean parsePython;
-
-  private EvaluationContext(EventHandler eventHandler, Environment env,
-      @Nullable ValidationEnvironment validationEnv, boolean parsePython) {
-    this.eventHandler = eventHandler;
-    this.env = env;
-    this.validationEnv = validationEnv;
-    this.parsePython = parsePython;
-  }
-
-  /**
-   * The fail fast handler, which throws a runtime exception whenever we encounter an error event.
-   */
-  public static final EventHandler FAIL_FAST_HANDLER = new EventHandler() {
-      @Override
-      public void handle(Event event) {
-        Preconditions.checkArgument(
-            !EventKind.ERRORS_AND_WARNINGS.contains(event.getKind()), event);
-      }
-    };
-
-  public static EvaluationContext newBuildContext(EventHandler eventHandler, Environment env,
-      boolean parsePython) {
-    return new EvaluationContext(eventHandler, env, null, parsePython);
-  }
-
-  public static EvaluationContext newBuildContext(EventHandler eventHandler, Environment env) {
-    return newBuildContext(eventHandler, env, false);
-  }
-
-  public static EvaluationContext newBuildContext(EventHandler eventHandler) {
-    return newBuildContext(eventHandler, new Environment());
-  }
-
-  public static EvaluationContext newSkylarkContext(
-      Environment env, ValidationEnvironment validationEnv) {
-    return new EvaluationContext(env.getEventHandler(), env, validationEnv, false);
-  }
-
-  public static EvaluationContext newSkylarkContext(EventHandler eventHandler) {
-    return newSkylarkContext(new SkylarkEnvironment(eventHandler), new ValidationEnvironment());
-  }
-
-  /** Base context for Skylark evaluation for internal use only, while initializing builtins */
-  static final EvaluationContext SKYLARK_INITIALIZATION = newSkylarkContext(FAIL_FAST_HANDLER);
-
-  @VisibleForTesting
-  public Environment getEnvironment() {
-    return env;
-  }
-
-  /** Mock package locator */
-  private static final class EmptyPackageLocator implements CachingPackageLocator {
-    @Override
-    public Path getBuildFileForPackage(PackageIdentifier packageName) {
-      return null;
-    }
-  }
-
-  /** An empty package locator */
-  private static final CachingPackageLocator EMPTY_PACKAGE_LOCATOR = new EmptyPackageLocator();
-
-  /** Create a Lexer without a supporting file */
-  @VisibleForTesting
-  Lexer createLexer(String... input) {
-    return new Lexer(ParserInputSource.create(Joiner.on("\n").join(input), null),
-        eventHandler);
-  }
-
-  /** Is this a Skylark evaluation context? */
-  public boolean isSkylark() {
-    return env.isSkylark();
-  }
-
-  /** Parse a string without a supporting file, returning statements and comments */
-  @VisibleForTesting
-  Parser.ParseResult parseFileWithComments(String... input) {
-    return isSkylark()
-        ? Parser.parseFileForSkylark(createLexer(input), eventHandler, null, validationEnv)
-        : Parser.parseFile(createLexer(input), eventHandler, EMPTY_PACKAGE_LOCATOR, parsePython);
-  }
-
-  /** Parse a string without a supporting file, returning statements only */
-  @VisibleForTesting
-  List<Statement> parseFile(String... input) {
-    return parseFileWithComments(input).statements;
-  }
-
-  /** Parse an Expression from string without a supporting file */
-  @VisibleForTesting
-  Expression parseExpression(String... input) {
-    return Parser.parseExpression(createLexer(input), eventHandler);
-  }
-
-  /** Evaluate an Expression */
-  @VisibleForTesting
-  Object evalExpression(Expression expression) throws EvalException, InterruptedException {
-    return expression.eval(env);
-  }
-
-  /** Evaluate an Expression as parsed from String-s */
-  Object evalExpression(String... input) throws EvalException, InterruptedException {
-    return evalExpression(parseExpression(input));
-  }
-
-  /** Parse a build (not Skylark) Statement from string without a supporting file */
-  @VisibleForTesting
-  Statement parseStatement(String... input) {
-    return Parser.parseStatement(createLexer(input), eventHandler);
-  }
-
-  /**
-   * Evaluate a Statement
-   * @param statement the Statement
-   * @return the value of the evaluation, if it's an Expression, or else null
-   */
-  @Nullable private Object eval(Statement statement) throws EvalException, InterruptedException {
-    if (statement instanceof ExpressionStatement) {
-      return evalExpression(((ExpressionStatement) statement).getExpression());
-    }
-    statement.exec(env);
-    return null;
-  }
-
-  /**
-   * Evaluate a list of Statement-s
-   * @return the value of the last statement if it's an Expression or else null
-   */
-  @Nullable private Object eval(List<Statement> statements)
-      throws EvalException, InterruptedException {
-    Object last = null;
-    for (Statement statement : statements) {
-      last = eval(statement);
-    }
-    return last;
-  }
-
-  /** Update a variable in the environment, in fluent style */
-  public EvaluationContext update(String varname, Object value) throws EvalException {
-    env.update(varname, value);
-    if (validationEnv != null) {
-      validationEnv.declare(varname, null);
-    }
-    return this;
-  }
-
-  /** Lookup a variable in the environment */
-  public Object lookup(String varname) throws NoSuchVariableException {
-    return env.lookup(varname);
-  }
-
-  /** Evaluate a series of statements */
-  public Object eval(String... input) throws EvalException, InterruptedException {
-    return eval(parseFile(input));
-  }
-}