Create ValidationEnvironment from Environment

Allow ValidationEnvironment to be created from initial Environment so that
there is no need to manually keep two different sets of constructors in synch.

--
MOS_MIGRATED_REVID=101588695

3 files changed, 26 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
index 5357d4d4db..3acbec1cab 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/Environment.java
@@ -101,6 +101,15 @@ public class Environment {
   protected Set<String> propagatingVariables = new HashSet<>();
 
   /**
+   * Is this a global environment?
+   * @return true if this is a global (top-level) environment
+   * as opposed to inside the body of a function
+   */
+  public boolean isGlobal() {
+    return true;
+  }
+
+  /**
    * An EventHandler for errors and warnings. This is not used in the BUILD language,
    * however it might be used in Skylark code called from the BUILD language.
    */
@@ -191,9 +200,10 @@ public class Environment {
    * Updates the value of variable "varname" in the environment, corresponding
    * to an {@link AssignmentStatement}.
    */
-  public void update(String varname, Object value) {
+  public Environment update(String varname, Object value) {
     Preconditions.checkNotNull(value, "update(value == null)");
     env.put(varname, value);
+    return this;
   }
 
   /**
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java
index c2923896fb..8e2a5c3acc 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkEnvironment.java
@@ -119,7 +119,7 @@ public class SkylarkEnvironment extends Environment implements Serializable {
    * Clones this Skylark global environment.
    */
   public SkylarkEnvironment cloneEnv(EventHandler eventHandler) {
-    Preconditions.checkArgument(isGlobalEnvironment());
+    Preconditions.checkArgument(isGlobal());
     SkylarkEnvironment newEnv = new SkylarkEnvironment(eventHandler, this.fileContentHashCode);
     for (Entry<String, Object> entry : env.entrySet()) {
       newEnv.env.put(entry.getKey(), entry.getValue());
@@ -142,7 +142,8 @@ public class SkylarkEnvironment extends Environment implements Serializable {
   /**
    * Returns true if this is a Skylark global environment.
    */
-  public boolean isGlobalEnvironment() {
+  @Override
+  public boolean isGlobal() {
     return parent == null;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java b/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
index 7aedca2c82..9b71f96acc 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/ValidationEnvironment.java
@@ -47,13 +47,21 @@ public class ValidationEnvironment {
 
   // Whether this validation environment is not modified therefore clonable or not.
   private boolean clonable;
-  
+
   /**
    * Tracks the number of nested for loops that contain the statement that is currently being
    * validated
    */
   private int loopCount = 0;
 
+  /**
+   * Create a ValidationEnvironment for a given global Environment
+   */
+  public ValidationEnvironment(Environment env) {
+    this(env.getVariableNames());
+    Preconditions.checkArgument(env.isGlobal());
+  }
+
   public ValidationEnvironment(Set<String> builtinVariables) {
     parent = null;
     variables.addAll(builtinVariables);
@@ -135,7 +143,7 @@ public class ValidationEnvironment {
   /**
    * Starts a session with temporarily disabled readonly checking for variables between branches.
    * This is useful to validate control flows like if-else when we know that certain parts of the
-   * code cannot both be executed. 
+   * code cannot both be executed.
    */
   public void startTemporarilyDisableReadonlyCheckSession() {
     futureReadOnlyVariables.add(new HashSet<String>());
@@ -190,14 +198,14 @@ public class ValidationEnvironment {
   public boolean isInsideLoop() {
     return (loopCount > 0);
   }
-  
+
   /**
    * Signals that the block of a for loop was entered
    */
   public void enterLoop()   {
     ++loopCount;
   }
-  
+
   /**
    * Signals that the block of a for loop was left
    *