Tomonaga Tokuyama Enterprises

List 1. PEG for DXF (spline only)

dxf ::= <header>:h (<spline> | <entity> | <entry>)+:c => (h, c)


newLine ::= ("\n" | "\r")
number ::= <digit>+:c => int(''.join(c))

label ::= <spaces>? <digit>+:t => int(''.join(t))
attrib ::= <spaces>? (~<newLine> <anything>)+:c => ''.join(c)
entry ::= <label>:l <newLine> (<newLine> | <attrib>):a => (l, a)
entryX :x ::= <entry>:e ?(e[0]==x) => e[1]
entryXX :xx ::= <entry>:e ?(e[0] in (xx)) => e[1]
entryXY :x :y ::= <entry>:e ?(e==(x,y))

vector ::= <entryX 10>:v0 <entryX 20>:v1 <entryX 30>:v2 => (float(v0),float(v1),float(v2))

entityBegin ::= <entryX 0>:v => v
nonEntityBegin ::= <entry>:e ?(e[0]!= 0)

entity ::= <entityBegin>:v <nonEntityBegin>* => v

spline ::=  <entityBegin>:v ?(v=="SPLINE")
            <entryXX (5,100,8,370,390,6, 62, 100, 210, 220, 230)>*
            <entryX 70>:flags
            <entryX 71>:deg
            <entryXX (72, 73, 74, 42, 43)>*
            <splineKnot>+:knots
            <vector>+:CPs
            <nonEntityBegin>*
            => ("Spline", {'flags': int(flags), 'deg': int(deg), 'knots':knots, 'points':CPs})
splineKnot ::= <entryX 40>:v => float(v)

header ::=  <entityBegin>:v ?(v=="SECTION")
            <entryXY 2 "HEADER">
            (~<entryXY 9 "$EXTMIN">)+
            <entryXY 9 "$EXTMIN">
            <vector>:extmin
            <entryXY 9 "$EXTMAX">
            <vector>:extmax
            <nonEntityBegin>*
            => {'min':extmin, 'max':extmax}

  ({'max': (41200.0, 850613.4907274337, 0.0), 'min': (-234117.469504671, 397400.0, 0.0)},
  ['ENDSEC', 'SECTION', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS',
   'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 'CLASS', 
   'CLASS', 'ENDSEC', 'SECTION', 'TABLE', 'VPORT', 'ENDTAB', 'TABLE', 'LTYPE', 'LTYPE', 'LTYPE',
   'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE', 'LTYPE',
   'ENDTAB', 'TABLE', 'LAYER', 'LAYER', 'LAYER', 'LAYER', 'LAYER', 'LAYER', 'LAYER', 'LAYER', 'LAYER',
   'LAYER', 'LAYER', 'LAYER', 'LAYER', 'ENDTAB', 'TABLE', 'STYLE', 'ENDTAB', 'TABLE', 'ENDTAB', 'TABLE',
    'ENDTAB', 'TABLE', 'APPID', 'ENDTAB', 'TABLE', 'DIMSTYLE', 'ENDTAB', 'TABLE', 'BLOCK_RECORD', 'BLOCK_RECORD', 
    'ENDTAB', 'ENDSEC', 'SECTION', 'BLOCK', 'ENDBLK', 'BLOCK', 'ENDBLK', 'ENDSEC', 'SECTION', 
    ('Spline',
     {'knots': [0.0, 0.0, 0.0, 1.0, 1.0, 2.0, 2.0, 3.0, 3.0, 4.0, 4.0, 5.0, 5.0, 6.0, 6.0, 7.0, 7.0, ....],
      'points': [(-12231.27794848819, 814215.11690494104, 0.0), (-10831.27794848819, 815215.11690494104, 0.0), ...],
      'deg': 2}
    ....

I tried out PyMeta for extracting spline curves from DXF files as Python data. I know PyMeta is too powerful for that simple task, but I got really interesting brain training thorough out this experience. Though human being can understand a grammar intuitively somehow, writing down it in a pure logical format that computers can understand (like List.1 above) was painful job and kind of a new world for me. I was fully impressed by design philosophy of OMeta.