1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
|
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Parse Graph Operations - Packrat Docs</title>
<link href="default.css" rel="stylesheet">
</head>
<body>
<h2>Parse Graph Operations</h2>
<a href="index.html">Return to Contents</a>
<p>While this uses a directed graph library with node and edge labels internally, it is rather
different from a usage point of view. A parse graph is designed around tokens (from
<em>Packrat.Tokens</em>) that can each have more tokens as children.</p>
<table>
<tr>
<td><pre>
procedure Assign
(Target : in out Parse_Graph;
Source : in Parse_Graph);
function Copy
(Source : in Parse_Graph)
return Parse_Graph;
procedure Move
(Target, Source : in out Parse_Graph);
</pre></td>
<td>Standard assignment operations that are common to most things in the Ada standard Container library.</td>
</tr>
<tr>
<td><pre>
function Is_Empty
(Container : in Parse_Graph)
return Boolean;
</pre></td>
<td>Tests whether a graph is empty.</td>
</tr>
<tr>
<td><pre>
procedure Clear
(Container : in out Parse_Graph);
</pre></td>
<td>Completely clears a graph, leaving it empty afterwards.</td>
</tr>
<tr>
<td><pre>
function Debug_String
(Container : in Parse_Graph)
return String;
</pre></td>
<td>Generate a string that shows a pretty printed structure of the graph in a similar way to page three of
the paper referenced in <a href="credits.html">Further Reading</a>.</td>
</tr>
<tr>
<td><pre>
function Contains
(Container : in Parse_Graph;
Token : in Traits.Tokens.Token_Type)
return Boolean;
function Contains
(Container : in Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
return Boolean;
function Contains
(Container : in Parse_Graph;
Grouping : in Token_Group)
return Boolean;
function Contains
(Container : in Parse_Graph;
Parent : in Traits.Tokens.Finished_Token_Type;
Subtokens : in Traits.Tokens.Finished_Token_Array)
return Boolean;
</pre></td>
<td>Tests for whether a graph contains various things.</td>
</tr>
<tr>
<td><pre>
function Reachable
(Container : in Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
return Boolean
with Pre => Container.Has_Root;
</pre></td>
<td>Checks whether a given finished token is reachable somehow from one or more of the root tokens of
the graph.</td>
</tr>
<tr>
<td><pre>
function All_Reachable
(Container : in Parse_Graph)
return Boolean
with Pre => Container.Has_Root;
</pre></td>
<td>Checks whether all tokens in the graph are reachable from one or more of the root tokens.</td>
</tr>
<tr>
<td><pre>
function Valid_Token
(Fin_Token : in Traits.Tokens.Finished_Token_Type)
return Boolean;
</pre></td>
<td>Checks whether the start and finish values of a token make sense, or in other words that the finish
value is no more than one less than the start value..</td>
</tr>
<tr>
<td><pre>
function Valid_Starts_Finishes
(Parent : in Traits.Tokens.Finished_Token_Type;
Subtokens : in Traits.Tokens.Finished_Token_Array)
return Boolean
with Pre => Subtokens'Length > 0;
</pre></td>
<td>Checks whether the various start and finish values of all the tokens make sense for being a parent
and a list of children. All the starts and finishes of individual tokens must make sense as in
<em>Valid_Token</em>, all the children tokens must be in order, the parent start and finish range must
fully cover all the children start and finish ranges, and none of the children start and finish ranges
can overlap each other.</td>
</tr>
<tr>
<td><pre>
function Loops_Introduced
(Container : in Parse_Graph;
Parent : in Traits.Tokens.Finished_Token_Type;
Subtokens : in Traits.Tokens.Finished_Token_Array)
return Boolean
with Pre => Subtokens'Length > 0 and
Valid_Starts_Finishes (Parent, Subtokens);
</pre></td>
<td>Checks whether adding the given parent and children group connection would introduce a loop into
the graph.</td>
</tr>
<tr>
<td><pre>
function Is_Sorted
(Finishes : in Traits.Tokens.Finish_Array)
return Boolean;
function Is_Sorted
(Positions : in Traits.Tokens.Finished_Token_Array)
return Boolean;
function Is_Sorted
(Groupings : in Token_Group_Array)
return Boolean;
</pre></td>
<td>Checks whether various sorts of arrays are sorted.</td>
</tr>
<tr>
<td><pre>
function No_Duplicates
(Finishes : in Traits.Tokens.Finish_Array)
return Boolean;
function No_Duplicates
(Positions : in Traits.Tokens.Finished_Token_Array)
return Boolean;
function No_Duplicates
(Groupings : in Token_Group_Array)
return Boolean;
</pre></td>
<td>Checks whether there are any duplicates in various sorts of arrays.</td>
</tr>
<tr>
<td><pre>
procedure Include
(Container : in out Parse_Graph;
Token : in Traits.Tokens.Token_Type)
with Post => Container.Contains (Token);
</pre></td>
<td>Adds a token to the graph. If the graph already contains the token, this does nothing.</td>
</tr>
<tr>
<td><pre>
procedure Connect
(Container : in out Parse_Graph;
Parent : in Traits.Tokens.Finished_Token_Type;
Subtokens : in Traits.Tokens.Finished_Token_Array)
with Pre => Subtokens'Length > 0 and
Valid_Starts_Finishes (Parent, Subtokens) and
not Container.Loops_Introduced (Parent, Subtokens);
</pre></td>
<td>Adds a connection group between a parent token and some children tokens in the graph. If
any of the tokens involved is not in the graph already they are first added. If the connection
already exists in the graph, this does nothing.</td>
</tr>
<tr>
<td><pre>
procedure Prune
(Container : in out Parse_Graph;
Token : in Traits.Tokens.Token_Type)
with Post => not Container.Contains (Token);
procedure Prune
(Container : in out Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
with Post => not Container.Contains (Position);
procedure Prune
(Container : in out Parse_Graph;
Grouping : in Token_Group)
with Post => not Container.Contains (Grouping);
</pre></td>
<td>Removes various things from a graph. No effort is made to remove anything made unreachable
by these operations.</td>
</tr>
<tr>
<td><pre>
procedure Delete_Unreachable
(Container : in out Parse_Graph)
with Pre => Container.Has_Root,
Post => Container.All_Reachable;
</pre></td>
<td>Removes all unreachable tokens, edges, and otherwise from a graph. Note that if the graph has
no root tokens then this will become equivalent to <em>Clear</em>.</td>
</tr>
<tr>
<td><pre>
function Has_Root
(Container : in Parse_Graph)
return Boolean;
</pre></td>
<td>Checks whether a graph contains a root token.</td>
</tr>
<tr>
<td><pre>
procedure Set_Root
(Container : in out Parse_Graph;
Tokens : in Traits.Tokens.Finished_Token_Array)
with Pre => (for all F of Tokens => Container.Contains (F.Token)),
Post => Container.Has_Root;
</pre></td>
<td>Sets one or more root tokens for a graph.</td>
</tr>
<tr>
<td><pre>
procedure Clear_Root
(Container : in out Parse_Graph)
with Post => not Container.Has_Root;
</pre></td>
<td>Removes all root tokens from the graph. Note that the graph will still contain the tokens,
they just won't be considered root tokens anymore.</td>
</tr>
<tr>
<td><pre>
function Root_Elements
(Container : in Parse_Graph)
return Traits.Tokens.Finished_Token_Array
with Pre => Container.Has_Root;
</pre></td>
<td>Retrieves all the root tokens for a given graph.</td>
</tr>
<tr>
<td><pre>
function Finish_List
(Container : in Parse_Graph;
Token : in Traits.Tokens.Token_Type)
return Traits.Tokens.Finish_Array
with Pre => Container.Contains (Token),
Post => Is_Sorted (Finish_List'Result) and
No_Duplicates (Finish_List'Result);
</pre></td>
<td>For a given unfinished token and a graph, returns all valid finishes that the token could take
such that the finished token is in the graph.</td>
</tr>
<tr>
<td><pre>
function Is_Leaf
(Container : in Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
return Boolean
with Pre => Container.Contains (Position);
</pre></td>
<td>Predicate to check whether a finished token is a leaf node in the graph. That is, whether it
has no children.</td>
</tr>
<tr>
<td><pre>
function Is_Branch
(Container : in Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
return Boolean
with Pre => Container.Contains (Position);
</pre></td>
<td>Predicate to check whether a finished token is a branch node in the graph. That is, whether it
has children.</td>
</tr>
<tr>
<td><pre>
function Subgroups
(Container : in Parse_Graph;
Position : in Traits.Tokens.Finished_Token_Type)
return Token_Group_Array
with Pre => Container.Contains (Position),
Post => Is_Sorted (Subgroups'Result) and
No_Duplicates (Subgroups'Result) and
(for all G of Subgroups'Result => Finish (G) = Position.Finish);
</pre></td>
<td>Returns an array of all the groups of children of a particular token in the graph. There will only
be multiple groups if the graph is ambiguous at this point.</td>
</tr>
<tr>
<td><pre>
function First_Index
(Grouping : in Token_Group)
return Positive;
function Last_Index
(Grouping : in Token_Group)
return Positive;
function Length
(Grouping : in Token_Group)
return Ada.Containers.Count_Type;
function Element
(Grouping : in Token_Group;
Index : in Positive)
return Traits.Tokens.Finished_Token_Type
with Pre => Index in First_Index (Grouping) .. Last_Index (Grouping);
</pre></td>
<td>These work as you would expect on an array/vector. <em>Element</em> returns a particular
child token in the given group.</td>
</tr>
<tr>
<td><pre>
function Elements
(Grouping : in Token_Group)
return Traits.Tokens.Finished_Token_Array
with Post => Is_Sorted (Elements'Result) and
Valid_Starts_Finishes (Parent (Grouping), Elements'Result);
</pre></td>
<td>Returns all the children tokens in the group as an array instead of a <em>Token_Group</em>.</td>
</tr>
<tr>
<td><pre>
function Parent
(Grouping : in Token_Group)
return Traits.Tokens.Finished_Token_Type;
</pre></td>
<td>Returns the parent token of the group.</td>
</tr>
<tr>
<td><pre>
function Finish
(Grouping : in Token_Group)
return Traits.Tokens.Finish_Type;
</pre></td>
<td>Returns the finishing position of the group, which is the same as the finish of the parent token.</td>
</tr>
<tr>
<td><pre>
function Is_Root_Ambiguous
(Container : in Parse_Graph)
return Boolean
with Pre => Container.Has_Root;
</pre></td>
<td>Checks whether the root tokens for a graph are ambiguous. The root is ambiguous if there are multiple
root tokens, or if there are multiple child groups attached to a root token.</td>
</tr>
<tr>
<td><pre>
function Is_Ambiguous
(Container : in Parse_Graph)
return Boolean;
</pre></td>
<td>Checks if the graph is ambiguous. That is, checks whether there are multiple root tokens or if
any token in the graph has multiple child groups attached to it.</td>
</tr>
<tr>
<td><pre>
function Ambiguities
(Container : in Parse_Graph;
Ambiguous_Root : out Boolean)
return Traits.Tokens.Finished_Token_Array
with Post => Is_Sorted (Ambiguities'Result) and
No_Duplicates (Ambiguities'Result);
</pre></td>
<td>Gives the parent tokens of all ambiguities in the graph.</td>
</tr>
<tr>
<td><pre>
function Isomorphic
(Left, Right : in Parse_Graph)
return Boolean
with Pre => Left.Has_Root and Right.Has_Root;
</pre></td>
<td>Checks whether the two graphs are isomorphic in structure. This means that the tokens and groups
are all the same except for any consistent offset in the start and finish values.</td>
</tr>
<tr>
<td><pre>
function Isomorphic_Subgraph
(Left_Graph : in Parse_Graph;
Left_Position : in Traits.Tokens.Finished_Token_Type;
Right_Graph : in Parse_Graph;
Right_Position : in Traits.Tokens.Finished_Token_Type)
return Boolean
with Pre => Left_Graph.Contains (Left_Position) and
Right_Graph.Contains (Right_Position);
</pre></td>
<td>Checks whether the subgraphs formed by the respective positions in each graph and all their connected
children are isomorphic. This means that all the tokens and groups in those subgraphs are all the same
except for any consistent offset in the start and finish values. Note that it is possible to check
for isomorphism between two subgraphs in the same graph.</td>
</tr>
</table>
</body>
</html>
|
