Pyparsing令牌源範圍

Question

如何在Pyparsing中以編程方式提取語法規則匹配的源範圍（開始和結束位置）？對於這個（子）規則，我不能使用setParseAction，因爲我正在檢查另一個回調中依次指定爲ParseAction的分析樹內容。我也缺少打印功能，人性化類似於pprint的方式，由parseString()返回的內容。我知道toList()，但我不確定此成員是否剝奪了有趣的信息，如上下文。

Answer 1

這裏是展示如何捕獲解析表達式的位置，並使用dump()，列出分析數據，並命名爲結果一些示例代碼：

from pyparsing import * 

# use an Empty to define a null token that just records its 
# own location in the input string 
locnMarker = Empty().leaveWhitespace().setParseAction(lambda s,l,t: l) 

# define a example expression and save the start and end locations 
markedInteger = locnMarker + Word(nums)('value') + locnMarker 

# assign named results for the start and end values, 
# and pop them out of the actual list of tokens 
def markStartAndEnd(s,l,t): 
    t['start'],t['end'] = t.pop(0),t.pop(-1) 
markedInteger.setParseAction(markStartAndEnd) 

# find all integers in the source string, and print 
# their value, start, and end locations; use dump() 
# to show the parsed tokens and any named results 
source = "ljsdlj2342 sadlsfj132 sldfj12321 sldkjfsldj 1232" 
for integer in markedInteger.searchString(source): 
    print integer.dump() 

打印：

['2342'] 
- end: 11 
- start: 6 
- value: 2342 
['132'] 
- end: 22 
- start: 18 
- value: 132 
['12321'] 
- end: 33 
- start: 27 
- value: 12321 
['1232'] 
- end: 48 
- start: 44 
- value: 1232