com.google.auto.value.processor.escapevelocity

Class Macro.MacroEvaluationContext

java.lang.Object

com.google.auto.value.processor.escapevelocity.Macro.MacroEvaluationContext

All Implemented Interfaces:

EvaluationContext

Enclosing class:

Macro

static class Macro.MacroEvaluationContext
extends java.lang.Object
implements EvaluationContext

The context for evaluation within macros. This wraps an existing EvaluationContext but intercepts reads of the macro's parameters so that they result in a call-by-name evaluation of whatever was passed as the parameter. For example, if you write...

 #macro (mymacro $x)
 $x $x
 #end
 #mymacro($foo.bar(23))
 

...then the #mymacro call will result in $foo.bar(23) being evaluated twice, once for each time $x appears. The way this works is that $x is a thunk. Historically a thunk is a piece of code to evaluate an expression in the context where it occurs, for call-by-name procedures as in Algol 60. Here, it is not exactly a piece of code, but it has the same responsibility.

Nested Class Summary

Nested classes/interfaces inherited from interface com.google.auto.value.processor.escapevelocity.EvaluationContext

EvaluationContext.PlainEvaluationContext

Field Summary

Fields

Modifier and Type	Field and Description
private EvaluationContext	originalEvaluationContext
private java.util.Map<java.lang.String,Node>	parameterThunks

Constructor Summary

Constructors

Constructor and Description
MacroEvaluationContext(java.util.Map<java.lang.String,Node> parameterThunks, EvaluationContext originalEvaluationContext)

Method Summary

Modifier and Type	Method and Description
java.lang.Object	getVar(java.lang.String var)
java.lang.Runnable	setVar(java.lang.String var, java.lang.Object value) Sets the given variable to the given value.
boolean	varIsDefined(java.lang.String var)

Methods inherited from class java.lang.Object

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

Field Detail

parameterThunks

private final java.util.Map<java.lang.String,Node> parameterThunks

originalEvaluationContext

private final EvaluationContext originalEvaluationContext

Constructor Detail

MacroEvaluationContext

MacroEvaluationContext(java.util.Map<java.lang.String,Node> parameterThunks,
                       EvaluationContext originalEvaluationContext)

Method Detail

getVar

public java.lang.Object getVar(java.lang.String var)

Specified by:

getVar in interface EvaluationContext

varIsDefined

public boolean varIsDefined(java.lang.String var)

Specified by:

varIsDefined in interface EvaluationContext

setVar

public java.lang.Runnable setVar(java.lang.String var,
                                 java.lang.Object value)

Description copied from interface: EvaluationContext

Sets the given variable to the given value.

Specified by:

setVar in interface EvaluationContext

Returns:

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 $x after #foreach ($x in ...).