36 lines
980 B
Smalltalk
36 lines
980 B
Smalltalk
|
"
|
||
|
|
A PPConditionalParser is a delegate parser that evaluates a block and if that returns true, the delegate parser is invoked and its result returned. If the block evaluates to false, the PPFailure is returned.
|
||
|
|
|
||
|
|
The block accepts one argument, context.
|
||
|
|
|
||
|
|
E.g.
|
||
|
|
('a' asParser if: [ :ctx | (ctx propertyAt: #myProperty) isNotNil ]) parse: 'a'
|
||
|
|
"
|
||
|
|
Class {
|
||
|
|
#name : 'PPConditionalParser',
|
||
|
|
#superclass : 'PPDelegateParser',
|
||
|
|
#instVars : [
|
||
|
|
'block'
|
||
|
|
],
|
||
|
|
#category : 'PetitParser-Parsers'
|
||
|
|
}
|
||
|
|
|
||
|
|
{ #category : 'instance creation' }
|
||
|
|
PPConditionalParser class >> on: aPPParser block: block [
|
||
|
|
^ (PPConditionalParser on: aPPParser)
|
||
|
|
block: block;
|
||
|
|
yourself
|
||
|
|
]
|
||
|
|
|
||
|
|
{ #category : 'accessing' }
|
||
|
|
PPConditionalParser >> block: aBlock [
|
||
|
|
block := aBlock
|
||
|
|
]
|
||
|
|
|
||
|
|
{ #category : 'parsing' }
|
||
|
|
PPConditionalParser >> parseOn: aPPContext [
|
||
|
|
^ (block value: aPPContext)
|
||
|
|
ifTrue: [ parser parseOn: aPPContext ]
|
||
|
|
ifFalse: [ PPFailure message: block asString, ' was not evaluated to true.' context: aPPContext ]
|
||
|
|
]
|