com.google.javascript.jscomp

Class CheckSideEffects

java.lang.Object

com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback

com.google.javascript.jscomp.CheckSideEffects

All Implemented Interfaces:

CompilerPass, HotSwapCompilerPass, NodeTraversal.Callback

final class CheckSideEffects
extends NodeTraversal.AbstractPostOrderCallback
implements HotSwapCompilerPass

Checks for non side effecting statements such as

 var s = "this string is "
         "continued on the next line but you forgot the +";
 x == foo();  // should that be '='?
 foo();;  // probably just a stray-semicolon. Doesn't hurt to check though
 

and generates warnings.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	CheckSideEffects.GetNoSideEffectExterns Get fully qualified function names which are marked with @nosideeffects TODO(ChadKillingsworth) Add support for object literals
(package private) static class	CheckSideEffects.StripProtection Remove side-effect sync functions.

Field Summary

Fields

Modifier and Type	Field and Description
private AbstractCompiler	compiler
private java.util.LinkedHashMap<java.lang.String,java.lang.String>	noSideEffectExterns
private java.util.List<Node>	problemNodes
(package private) static java.lang.String	PROTECTOR_FN
private boolean	protectSideEffectFreeCode
private boolean	report
(package private) static DiagnosticType	USELESS_CODE_ERROR

Constructor Summary

Constructors

Constructor and Description
CheckSideEffects(AbstractCompiler compiler, boolean report, boolean protectSideEffectFreeCode)

Method Summary

Modifier and Type	Method and Description
private void	addExtern()
void	hotSwapScript(Node scriptRoot, Node originalRoot) Process the JS with root node root.
void	process(Node externs, Node root) Process the JS with root node root.
private void	protectSideEffects() Protect side-effect free nodes by making them parameters to a extern function call.
void	visit(NodeTraversal t, Node n, Node parent) Visits a node in postorder (after its children have been visited).

Methods inherited from class com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback

shouldTraverse

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

USELESS_CODE_ERROR

static final DiagnosticType USELESS_CODE_ERROR

PROTECTOR_FN

static final java.lang.String PROTECTOR_FN

See Also:

Constant Field Values

report

private final boolean report

problemNodes

private final java.util.List<Node> problemNodes

noSideEffectExterns

private final java.util.LinkedHashMap<java.lang.String,java.lang.String> noSideEffectExterns

compiler

private final AbstractCompiler compiler

protectSideEffectFreeCode

private final boolean protectSideEffectFreeCode

Constructor Detail

CheckSideEffects

CheckSideEffects(AbstractCompiler compiler,
                 boolean report,
                 boolean protectSideEffectFreeCode)

Method Detail

process

public void process(Node externs,
                    Node root)

Description copied from interface: CompilerPass

Process the JS with root node root. Can modify the contents of each Node tree

Specified by:

process in interface CompilerPass

Parameters:

externs - Top of external JS tree

root - Top of JS tree

hotSwapScript

public void hotSwapScript(Node scriptRoot,
                          Node originalRoot)

Description copied from interface: HotSwapCompilerPass

Process the JS with root node root. This is supposed to be significantly faster compared to corresponding full-compiler passes.

Specified by:

hotSwapScript in interface HotSwapCompilerPass

Parameters:

scriptRoot - Root node corresponding to the file that is modified, should be of type Token.SCRIPT.

originalRoot - Root node corresponding to the original version of the file that is modified. Should be of type token.SCRIPT.

visit

public void visit(NodeTraversal t,
                  Node n,
                  Node parent)

Description copied from interface: NodeTraversal.Callback

Visits a node in postorder (after its children have been visited). A node is visited only if all its parents should be traversed (NodeTraversal.Callback.shouldTraverse(NodeTraversal, Node, Node)).

Implementations can have side effects (e.g. modifying the parse tree).

Specified by:

visit in interface NodeTraversal.Callback

protectSideEffects

private void protectSideEffects()

Protect side-effect free nodes by making them parameters to a extern function call. This call will be removed after all the optimizations passes have run.

addExtern

private void addExtern()