com.google.javascript.jscomp

Class RescopeGlobalSymbols

java.lang.Object

com.google.javascript.jscomp.RescopeGlobalSymbols

All Implemented Interfaces:

CompilerPass

final class RescopeGlobalSymbols
extends java.lang.Object
implements CompilerPass

Finds all references to global symbols and rewrites them to be property accesses to a special object with the same name as the global symbol. Given the name of the global object is NS

 var a = 1; function b() { return a }

becomes

 NS.a = 1; NS.b = function b() { return NS.a }

This allows splitting code into modules that depend on each other's global symbols, without using polluting JavaScript's global scope with those symbols. You typically define just a single global symbol, wrap each module in a function wrapper, and pass the global symbol around, eg,

 var uniqueNs = uniqueNs || {}; 

 (function (NS) { ...your module code here... })(uniqueNs); 

This compile step requires moveFunctionDeclarations to be turned on to guarantee semantics.

For lots of examples, see the unit test.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	RescopeGlobalSymbols.FindCrossModuleNamesCallback Find all global names that are used in more than one module.
private class	RescopeGlobalSymbols.FindNamesReferencingThis Builds the maybeReferencesThis set of names that may reference a function that references this.
private class	RescopeGlobalSymbols.MakeExternsReferenceWindowExplicitly Rewrites extern names to be explicit children of window instead of only implicitly referencing it.
private class	RescopeGlobalSymbols.RemoveGlobalVarCallback Removes every occurrence of var that declares a global variable.
private class	RescopeGlobalSymbols.RewriteGlobalFunctionStatementsToVarAssignmentsCallback Rewrites function statements to var statements + assignment.
private class	RescopeGlobalSymbols.RewriteScopeCallback Visits each NAME token and checks whether it refers to a global variable.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	addExtern
private boolean	assumeCrossModuleNames
private AbstractCompiler	compiler
private java.util.Set<java.lang.String>	crossModuleNames
private static java.lang.String	DISAMBIGUATION_SUFFIX
private java.lang.String	globalSymbolNamespace
private java.util.Set<java.lang.String>	maybeReferencesThis
private static java.util.Set<java.lang.String>	SPECIAL_EXTERNS
private static java.lang.String	WINDOW

Constructor Summary

Constructors

Constructor and Description
RescopeGlobalSymbols(AbstractCompiler compiler, java.lang.String globalSymbolNamespace, boolean assumeCrossModuleNames) Constructor for the RescopeGlobalSymbols compiler pass.
RescopeGlobalSymbols(AbstractCompiler compiler, java.lang.String globalSymbolNamespace, boolean addExtern, boolean assumeCrossModuleNames) Constructor for the RescopeGlobalSymbols compiler pass for use in testing.

Method Summary

Modifier and Type	Method and Description
private void	addExternForGlobalSymbolNamespace()
private boolean	isCrossModuleName(java.lang.String name)
void	process(Node externs, Node root) Process the JS with root node root.

Methods inherited from class java.lang.Object

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

Field Detail

DISAMBIGUATION_SUFFIX

private static final java.lang.String DISAMBIGUATION_SUFFIX

See Also:

Constant Field Values

WINDOW

private static final java.lang.String WINDOW

See Also:

Constant Field Values

SPECIAL_EXTERNS

private static final java.util.Set<java.lang.String> SPECIAL_EXTERNS

compiler

private final AbstractCompiler compiler

globalSymbolNamespace

private final java.lang.String globalSymbolNamespace

addExtern

private final boolean addExtern

assumeCrossModuleNames

private final boolean assumeCrossModuleNames

crossModuleNames

private final java.util.Set<java.lang.String> crossModuleNames

maybeReferencesThis

private final java.util.Set<java.lang.String> maybeReferencesThis

Constructor Detail

RescopeGlobalSymbols

RescopeGlobalSymbols(AbstractCompiler compiler,
                     java.lang.String globalSymbolNamespace,
                     boolean assumeCrossModuleNames)

Constructor for the RescopeGlobalSymbols compiler pass.

Parameters:

compiler - The JSCompiler, for reporting code changes.

globalSymbolNamespace - Name of namespace into which all global symbols are transferred.

assumeCrossModuleNames - If true, all global symbols will be assumed cross module boundaries and thus require renaming.

RescopeGlobalSymbols

RescopeGlobalSymbols(AbstractCompiler compiler,
                     java.lang.String globalSymbolNamespace,
                     boolean addExtern,
                     boolean assumeCrossModuleNames)

Constructor for the RescopeGlobalSymbols compiler pass for use in testing.

Parameters:

compiler - The JSCompiler, for reporting code changes.

globalSymbolNamespace - Name of namespace into which all global symbols are transferred.

addExtern - If true, the compiler will consider the globalSymbolNamespace an extern name.

assumeCrossModuleNames - If true, all global symbols will be assumed cross module boundaries and thus require renaming. VisibleForTesting

Method Detail

isCrossModuleName

private boolean isCrossModuleName(java.lang.String name)

addExternForGlobalSymbolNamespace

private void addExternForGlobalSymbolNamespace()

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