source: proto/matchparens/pdfparenmatch.pablo @ 3030

Last change on this file since 3030 was 3030, checked in by cameron, 6 years ago

Tighten up paren match prototypes

File size: 1.7 KB
Line 
1#
2# Recursive Parenthesis Matching
3#
4#
5# Robert D. Cameron
6# October 14, 2012
7#
8
9class Basis_bits():     
10        bit_0 = 0
11        bit_1 = 0
12        bit_2 = 0
13        bit_3 = 0
14        bit_4 = 0
15        bit_5 = 0
16        bit_6 = 0
17        bit_7 = 0
18
19class Lex ():
20        LParen = 0
21        RParen = 0
22       
23class Matches() :
24        closed = 0
25        instring = 0
26        error = 0
27
28
29def Classify_bytes(basis_bits, lex): 
30        temp1 = (basis_bits.bit_0 | basis_bits.bit_1)
31        temp2 = (basis_bits.bit_2 &~ basis_bits.bit_3)
32        temp3 = (temp2 &~ temp1)
33        temp4 = (basis_bits.bit_4 &~ basis_bits.bit_5)
34        temp5 = (basis_bits.bit_6 | basis_bits.bit_7)
35        temp6 = (temp4 &~ temp5)
36        lex.LParen = (temp3 & temp6)
37        temp7 = (basis_bits.bit_7 &~ basis_bits.bit_6)
38        temp8 = (temp4 & temp7)
39        lex.RParen = (temp3 & temp8)
40       
41def Match_Parens(lex, matches):
42        parens = lex.LParen | lex.RParen
43        Lscan = pablo.AdvanceThenScanTo(lex.LParen, parens)
44        Rscan = pablo.AdvanceThenScanTo(lex.RParen, parens)
45        matches.instring = pablo.ExclusiveSpan(lex.LParen, Lscan)
46        matches.closed = Lscan & lex.RParen
47        matches.error = pablo.atEOF(Lscan)
48        unclosed = Lscan & lex.LParen | Rscan & lex.RParen
49        while unclosed:
50                unclosedLParen = unclosed & lex.LParen
51                unclosedRParen = unclosed & lex.RParen
52                Lscan = pablo.AdvanceThenScanTo(unclosedLParen, unclosed)
53                Rscan = pablo.AdvanceThenScanTo(unclosedRParen, unclosed)
54                matches.instring |= pablo.SpanUpTo(unclosedLParen, Lscan)
55                matches.closed |= Lscan & lex.RParen
56                matches.error |= pablo.atEOF(Lscan)
57                unclosed = Lscan & lex.LParen | Rscan & lex.RParen
58        #
59        # Any closing paren that was not actually used to close
60        # an opener is in error.
61        matches.error = matches.error | (lex.RParen &~ matches.closed)
62
63
64def Main(basis_bits, lex, matches):
65        Classify_bytes(basis_bits, lex)
66        Match_Parens(lex, matches)
67
68
Note: See TracBrowser for help on using the repository browser.