how to parse multiple lines using ruby treetop?

Question

I am new to ruby and treetop.

I went through this tutorial and came up with the following set of rules.

grammar Sexp

  rule body
    commentPortString *(I am stuck here)*
  end

  rule interface
    space? (intf / intfWithSize) space? ('\n' / end_of_file) <Interface>
  end

  rule commentPortString
    space? '//' space portString space? ('\n' / end_of_file) <CommentPortString>
  end

  rule portString
    'Port' space? '.' <PortString>
  end

  rule expression
    space? '(' body ')' space? <Expression>
  end

  rule intf
    (input / output) space wire:wireName space? ';' <Intf>
  end

  rule intfWithSize
    (input / output) space? width:ifWidth space? wire:wireName space? ';' <IntfWithSize>
  end

  rule input
    'input'
  end

  rule output
    'output'
  end

  rule ifWidth
    '[' space? msb:digits space? ':' space? lsb:digits ']' <IfWidth>
  end

  rule digits
    [0-9]+
  end

  rule integer
    ('+' / '-')? [0-9]+ <IntegerLiteral>
  end

  rule float
    ('+' / '-')? [0-9]+ (('.' [0-9]+) / ('e' [0-9]+)) <FloatLiteral>
  end

  rule string
    '"' ('\"' / !'"' .)* '"' <StringLiteral>
  end

  rule signalTypeString
    '"' if_sig_name:signalType '"' <SignalTypeString>
  end

  rule signalType
    [a-zA-Z] [a-zA-Z0-9_]* (receiveLiteral / transmitLiteral) <SignalType>
  end

  rule receiveLiteral
    '.receive'
  end

  rule transmitLiteral
    '.transmit'
  end

  rule identifier
    [a-zA-Z\=\*] [a-zA-Z0-9_\=\*]* <Identifier>
  end

  rule wireName
    [a-zA-Z] [a-zA-Z0-9_]* <WireName>
  end

  rule non_space
    !space .
  end

  rule space
    [\s\t]+
  end

  rule newLine
    [\n\r]+
  end

  rule end_of_file
    !.
  end

end

I want the parser to extract out blobs such as the one below. It would always start with Port. and end with a blank line.

    // Port.
    output        send;
    input         free;
    output        fgcg;
    output[  2:0] state_id;
    output[  1:0] stream_id;
`ifdef SIMULATION
    output[ 83:0] dbg_id;
`endif

The rules mentioned above can identify all the lines in the text when passed individually but I am unable to extract out the blob. Also I just want to extract out the matching text and ignore the rest.

Can someone point me in the right direction please.

Answer 1

Is something like below along the lines you're looking for. It's hard to understand your problem fully without a little more information.

The space rule includes \s which includes \n already, so if you're looking for another \n, it won't parse correctly. If you modify the space rule to be [^\S\n]+ it will exclude \n so you can look for it explicitly.

If you're looking for a completely blank line to end the Port. block, you should look explicitly for "\n" ("\n" / end_of_file).

Hope that makes sense...

grammar Sexp

  rule body
    commentPortString interface* portEnd
  end

  rule interface
    space? (intf / intfWithSize) space? "\n" <Interface>
  end

  rule commentPortString
    space? '//' space? portString space? "\n" <CommentPortString>
  end

  rule portString
    'Port' space? '.' <PortString>
  end

  # Port block ends with a blank line
  rule portEnd
    "\n" / end_of_file
  end

  rule expression
    space? '(' body ')' space? <Expression>
  end

  rule intf
    (input / output) space wire:wireName space? ';' <Intf>
  end

  rule intfWithSize
    (input / output) space? width:ifWidth space? wire:wireName space? ';' <IntfWithSize>
  end

  rule input
    'input'
  end

  rule output
    'output'
  end

  rule ifWidth
    '[' space? msb:digits space? ':' space? lsb:digits ']' <IfWidth>
  end

  rule digits
    [0-9]+
  end

  rule integer
    ('+' / '-')? [0-9]+ <IntegerLiteral>
  end

  rule float
    ('+' / '-')? [0-9]+ (('.' [0-9]+) / ('e' [0-9]+)) <FloatLiteral>
  end

  rule string
    '"' ('\"' / !'"' .)* '"' <StringLiteral>
  end

  rule signalTypeString
    '"' if_sig_name:signalType '"' <SignalTypeString>
  end

  rule signalType
    [a-zA-Z] [a-zA-Z0-9_]* (receiveLiteral / transmitLiteral) <SignalType>
  end

  rule receiveLiteral
    '.receive'
  end

  rule transmitLiteral
    '.transmit'
  end

  rule identifier
    [a-zA-Z\=\*] [a-zA-Z0-9_\=\*]* <Identifier>
  end

  rule wireName
    [a-zA-Z] [a-zA-Z0-9_]* <WireName>
  end

  rule non_space
    !space .
  end

  rule space
    [^\S\n]+
  end

  rule newLine
    [\n\r]+
  end

  rule end_of_file
    !.
  end

end