Pyparsing 发现比预期更多的匹配项

Question

我正在编写代码来解析基本计算机指令行。我的输入字符串是这样的 ADD(input1,input2) DEL(input3), SUB(input1,input2) INS(input3)

我期待这样的结果：

<line>
  <instruction>
    <type>ADD</type>
    <args>
      <ITEM>input1</ITEM>
      <ITEM>input2</ITEM>
    </args>
  </instruction>
  <instruction>
    <type>DEL</type>
    <args>
      <ITEM>input3</ITEM>
    </args>
  </instruction>
</line>
<line>
  <instruction>
    <type>SUB</type>
    <args>
      <ITEM>input1</ITEM>
      <ITEM>input2</ITEM>
    </args>
  </instruction>
  <instruction>
    <type>INS</type>
    <args>
      <ITEM>input3</ITEM>
    </args>
  </instruction>
</line>

我的实际结果具有我正在寻找的一般结构，但是行和指令解析器似乎在错误的位置匹配，或者标签可能出现在错误的位置。

实际结果：

<line>
  <line>
    <instruction>
      <type>ADD</type>
      <args>
        <ITEM>input1</ITEM>
        <ITEM>input2</ITEM>
      </args>
    </instruction>
    <instruction>
      <type>DEL</type>
      <args>
        <ITEM>input3</ITEM>
      </args>
    </instruction>
  </line>
  <instruction>
    <instruction>
      <type>SUB</type>
      <args>
        <ITEM>input1</ITEM>
        <ITEM>input2</ITEM>
      </args>
    </instruction>
    <instruction>
      <type>INS</type>
      <args>
        <ITEM>input3</ITEM>
      </args>
    </instruction>
  </instruction>
</line>

结果转储

[[['OTE', ['output1']]], [['XIO', ['input2']], ['OTE', ['output2']]]]
- branch: [[['OTE', ['output1']]], [['XIO', ['input2']], ['OTE', ['output2']]]]
  [0]:
    [['OTE', ['output1']]]
    - instruction: ['OTE', ['output1']]
      - args: ['output1']
      - type: 'OTE'
  [1]:
    [['XIO', ['input2']], ['OTE', ['output2']]]
    - instruction: ['OTE', ['output2']]
      - args: ['output2']
      - type: 'OTE'

出于某种原因，行匹配整个结构，第二行指令作为单个指令组匹配。我尝试在 instruction 行上使用 .setDebug() 函数，但我不确定如何解释输出。我不明白为什么最后行应该匹配为一条指令，因为它不遵循 Word(Word) 模式。

我的代码：

#!python3
from pyparsing import nestedExpr,alphas,Word,Literal,OneOrMore,alphanums,delimitedList,Group,Forward

theInput = r"ADD(input1,input2) DEL(input3), SUB(input1,input2) INS(input3)"

instructionType = Word(alphanums+"_")("type")
argument = Word(alphanums+"_[].")
arguments = Group(delimitedList(argument))("args")
instruction = Group(instructionType + Literal("(").suppress() + arguments + Literal(")").suppress())("instruction")

line = (delimitedList(Group(OneOrMore(instruction))))("line")

parsedInput = line.parseString(theInput).asXML()
print(parsedInput)

调试输出：

Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 0(1,1)
Matched Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) -> [['ADD', ['input1', 'input2']]]
Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 18(1,19)
Matched Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) -> [['DEL', ['input3']]]
Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 30(1,31)
Exception raised:Expected W:(ABCD...) (at char 30), (line:1, col:31)
Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 32(1,33)
Matched Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) -> [['SUB', ['input1', 'input2']]]
Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 50(1,51)
Matched Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) -> [['INS', ['input3']]]
Match Group:({W:(ABCD...) Suppress:("(") Group:(W:(ABCD...) [, W:(ABCD...)]...) Suppress:(")")}) at loc 62(1,63)
Exception raised:Expected W:(ABCD...) (at char 62), (line:1, col:63)

我做错了什么？

Answer 1

您发布的代码的转储输出如下所示：

ADD(input1,input2) DEL(input3), SUB(input1,input2) INS(input3)

[[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
- line: [[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
  [0]:
    [['ADD', ['input1', 'input2']], ['DEL', ['input3']]]
    - instruction: ['DEL', ['input3']]
      - args: ['input3']
      - type: 'DEL'
  [1]:
    [['SUB', ['input1', 'input2']], ['INS', ['input3']]]
    - instruction: ['INS', ['input3']]
      - args: ['input3']
      - type: 'INS'

我们可以在 dump() 输出中看到所有指令都已解析，但只有每组中的最后一条指令显示在 "instruction" 名称下。发生这种情况是因为，就像 Python 字典一样，当多个值（如您可能在 ZeroOrMore 或 OneOrMore 中获得的值）被赋予相同的键时，只保留最后一个值。

有两种解决方法。一种是删除 ("instruction") 结果名称，这样您就可以在每个子列表中获得已解析的指令：

[[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
- line: [[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
  [0]:
    [['ADD', ['input1', 'input2']], ['DEL', ['input3']]]
    [0]:
      ['ADD', ['input1', 'input2']]
      - args: ['input1', 'input2']
      - type: 'ADD'
    [1]:
      ['DEL', ['input3']]
      - args: ['input3']
      - type: 'DEL'
  [1]:
    [['SUB', ['input1', 'input2']], ['INS', ['input3']]]
    [0]:
      ['SUB', ['input1', 'input2']]
      - args: ['input1', 'input2']
      - type: 'SUB'
    [1]:
      ['INS', ['input3']]
      - args: ['input3']
      - type: 'INS'

在 pyparsing 中，有时应该为给定名称保存多个值。 setResultsName() 方法有一个可选参数 listAllMatches 可以启用此行为。使用 setResultsName 的可调用快捷方式时，您不能传递 listAllMatches=True - 相反，结果名称以“*”结尾：

instruction = Group(instructionType 
                                + Literal("(").suppress() 
                                + arguments 
                                + Literal(")").suppress())("instruction*")

这给出了这个输出：

[[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
- line: [[['ADD', ['input1', 'input2']], ['DEL', ['input3']]], [['SUB', ['input1', 'input2']], ['INS', ['input3']]]]
  [0]:
    [['ADD', ['input1', 'input2']], ['DEL', ['input3']]]
    - instruction: [['ADD', ['input1', 'input2']], ['DEL', ['input3']]]
      [0]:
        ['ADD', ['input1', 'input2']]
        - args: ['input1', 'input2']
        - type: 'ADD'
      [1]:
        ['DEL', ['input3']]
        - args: ['input3']
        - type: 'DEL'
  [1]:
    [['SUB', ['input1', 'input2']], ['INS', ['input3']]]
    - instruction: [['SUB', ['input1', 'input2']], ['INS', ['input3']]]
      [0]:
        ['SUB', ['input1', 'input2']]
        - args: ['input1', 'input2']
        - type: 'SUB'
      [1]:
        ['INS', ['input3']]
        - args: ['input3']
        - type: 'INS'

您可以选择您更喜欢的方法。

Pyparsing 发现比预期更多的匹配项

Pyparsing finding more matches than expected

pyparsing

python-3.x