1page_util_peg(n) Parser generator tools page_util_peg(n)
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8 page_util_peg - page PEG transformation utilities
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11 package require page::util::peg ?0.1?
12 package require snit
14 ::page::util::peg::symbolNodeOf tree node
16 ::page::util::peg::symbolOf tree node
18 ::page::util::peg::updateUndefinedDueRemoval tree
20 ::page::util::peg::flatten treequery tree
22 ::page::util::peg::getWarnings tree
24 ::page::util::peg::printWarnings msg
26 ::page::util::peg::peOf tree eroot
28 ::page::util::peg::printTclExpr pe
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34 This package provides a few common operations to PEG transformations.
35 They assume a Normalized PE Grammar Tree as input, see the package
36 page::util::norm::peg, possibly augmented with attributes coming from
37 transformations not in conflict with the base definition.
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40 ::page::util::peg::symbolNodeOf tree node
41 Given an arbitrary expression node in the AST tree it determines
42 the node (itself or an ancestor) containing the name of the non‐
43 terminal symbol the node belongs to, and returns its id. The
44 result is either the root of the tree (for the start expres‐
45 sion), or a definition node.
46 ::page::util::peg::symbolOf tree node
48 As ::page::util::peg::symbolNodeOf, but returns the symbol name
49 instead of the node.
50 ::page::util::peg::updateUndefinedDueRemoval tree
52 The removal of nodes in the AST tree can cause symbols to lose
53 one or more users.
54 A used by B and C,
56 B is reachable,
57 C is not,
58 so A now loses the node in the expression for C calling it,
60 or rather, not calling it anymore.
61 This command updates the cross-references and which nonterminals
63 are now undefined.
64 ::page::util::peg::flatten treequery tree
66 This commands flattens nested sequence and choice operators in
67 the AST tree, re-using the treeql object treequery to run the
68 query determining which nodes to cut.
69 ::page::util::peg::getWarnings tree
71 This command looks at the attributes of the AST tree for prob‐
72 lems with the grammar and issues warnings. They do not prevent
73 us from writing the grammar, but still represent problems with
74 it the user should be made aware of.
75 The result of the command is a dictionary mapping nonterminal
77 names to their associated warnings.
78 ::page::util::peg::printWarnings msg
80 The argument of the command is a dictionary mapping nonterminal
81 names to their associated warnings, as generated by, for exam‐
82 ple, the command ::page::util::peg::getWarnings.
83 The warnings contained therein are formatted and then printed
85 via the log command page_info. This means that this command can
86 be used only from within a plugin managed by the package
87 page::pluginmgr.
88 ::page::util::peg::peOf tree eroot
90 This command converts the parsing expression starting at the
91 node eroot in the AST tree into a nested list. The exact syntax
92 of this list specified by the package grammar::peg.
93 ::page::util::peg::printTclExpr pe
95 This command converts the parsing expression contained in the
96 nested list pe into a Tcl string which can be placed into a Tcl
97 script. See the package grammar::peg for the exact syntax of
98 pe.
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101 This document, will undoubtedly contain bugs and other problems.
102 Please report such in the category page of the Tcllib SF Trackers
103 [http://sourceforge.net/tracker/?group_id=12883]. Please also report
104 any ideas for enhancements you may have.
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107 PEG, page, parser generator, parsing expression grammar, text process‐
108 ing, transformation
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111 Copyright (c) 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net>
112page 1.0 page_util_peg(n)