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dea4d055 MW |
1 | ;;; -*-lisp-*- |
2 | ;;; | |
3 | ;;; Protocol for lexical analysis | |
4 | ;;; | |
5 | ;;; (c) 2009 Straylight/Edgeware | |
6 | ;;; | |
7 | ||
8 | ;;;----- Licensing notice --------------------------------------------------- | |
9 | ;;; | |
e0808c47 | 10 | ;;; This file is part of the Sensible Object Design, an object system for C. |
dea4d055 MW |
11 | ;;; |
12 | ;;; SOD is free software; you can redistribute it and/or modify | |
13 | ;;; it under the terms of the GNU General Public License as published by | |
14 | ;;; the Free Software Foundation; either version 2 of the License, or | |
15 | ;;; (at your option) any later version. | |
16 | ;;; | |
17 | ;;; SOD is distributed in the hope that it will be useful, | |
18 | ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ;;; GNU General Public License for more details. | |
21 | ;;; | |
22 | ;;; You should have received a copy of the GNU General Public License | |
23 | ;;; along with SOD; if not, write to the Free Software Foundation, | |
24 | ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | ||
26 | (cl:in-package #:sod) | |
27 | ||
28 | ;;;-------------------------------------------------------------------------- | |
239fa5bd | 29 | ;;; Class definition. |
dea4d055 | 30 | |
239fa5bd MW |
31 | (export 'sod-token-scanner) |
32 | (defclass sod-token-scanner (token-scanner) | |
33 | ((char-scanner :initarg :char-scanner :reader token-scanner-char-scanner)) | |
dea4d055 | 34 | (:documentation |
239fa5bd | 35 | "A token scanner for SOD input files. |
dea4d055 | 36 | |
239fa5bd MW |
37 | Not a lot here, apart from a character scanner to read from and the |
38 | standard token scanner infrastructure.")) | |
dea4d055 | 39 | |
dea4d055 | 40 | ;;;-------------------------------------------------------------------------- |
239fa5bd MW |
41 | ;;; Indicators and error messages. |
42 | ||
1d8cc67a MW |
43 | (defvar *indicator-map* (make-hash-table) |
44 | "Hash table mapping indicator objects to human-readable descriptions.") | |
45 | ||
239fa5bd MW |
46 | (export 'define-indicator) |
47 | (defun define-indicator (indicator description) | |
48 | "Associate an INDICATOR with its textual DESCRIPTION. | |
49 | ||
50 | Updates the the `*indicator-map*'." | |
51 | (setf (gethash indicator *indicator-map*) description) | |
52 | indicator) | |
53 | ||
54 | (export 'syntax-error) | |
d63df20a | 55 | (defun syntax-error (scanner expected &key (continuep t) location) |
239fa5bd MW |
56 | "Signal a (maybe) continuable syntax error." |
57 | (labels ((show-token (type value) | |
58 | (if (characterp type) | |
59 | (format nil "~/sod::show-char/" type) | |
60 | (case type | |
61 | (:id (format nil "<identifier~@[ `~A'~]>" value)) | |
048d0b2d | 62 | (:int "<integer-literal>") |
239fa5bd MW |
63 | (:string "<string-literal>") |
64 | (:char "<character-literal>") | |
65 | (:eof "<end-of-file>") | |
66 | (:ellipsis "`...'") | |
67 | (t (format nil "<? ~S~@[ ~S~]>" type value))))) | |
68 | (show-expected (thing) | |
69 | (acond ((gethash thing *indicator-map*) it) | |
70 | ((atom thing) (show-token thing nil)) | |
71 | ((eq (car thing) :id) | |
72 | (format nil "`~A'" (cadr thing))) | |
73 | (t (format nil "<? ~S>" thing))))) | |
d63df20a MW |
74 | (funcall (if continuep #'cerror*-with-location #'error-with-location) |
75 | (or location scanner) | |
239fa5bd MW |
76 | "Syntax error: ~ |
77 | expected ~{~#[<bug>~;~A~;~A or ~A~:;~A, ~]~} ~ | |
78 | but found ~A" | |
79 | (mapcar #'show-expected expected) | |
80 | (show-token (token-type scanner) (token-value scanner))))) | |
81 | ||
82 | (export 'lexer-error) | |
d63df20a | 83 | (defun lexer-error (char-scanner expected &key location) |
239fa5bd | 84 | "Signal a continuable lexical error." |
d63df20a MW |
85 | (cerror*-with-location (or location char-scanner) |
86 | "Lexical error: ~ | |
7524b4b2 | 87 | ~:[unexpected~;~ |
3c46cb3a MW |
88 | expected ~:*~{~#[~;~A~;~A or ~A~:;~ |
89 | ~@{~A, ~#[~;or ~A~]~}~]~} ~ | |
7524b4b2 MW |
90 | but found~] ~ |
91 | ~/sod::show-char/" | |
239fa5bd MW |
92 | (mapcar (lambda (exp) |
93 | (typecase exp | |
94 | (character (format nil "~/sod::show-char/" exp)) | |
95 | (string (format nil "`~A'" exp)) | |
96 | ((cons (eql :digit) *) (format nil "<radix-~A digit>" | |
97 | (cadr exp))) | |
98 | ((eql :eof) "<end-of-file>") | |
99 | ((eql :any) "<character>") | |
100 | (t (format nil "<? ~S>" exp)))) | |
101 | expected) | |
102 | (and (not (scanner-at-eof-p char-scanner)) | |
26c5ecfe | 103 | (scanner-current-char char-scanner)))) |
dea4d055 | 104 | |
33b5686f | 105 | (export 'skip-until) |
048d0b2d MW |
106 | (defparse skip-until (:context (context token-scanner-context) |
107 | (&key (keep-end nil keep-end-p)) | |
108 | &rest token-types) | |
109 | "Discard tokens until we find one listed in TOKEN-TYPES. | |
110 | ||
111 | If KEEP-END is true then retain the found token for later; otherwise | |
112 | discard it. KEEP-END defaults to true if multiple TOKEN-TYPES are given; | |
113 | otherwise false. If end-of-file is encountered then the indicator list is | |
114 | simply the list of TOKEN-TYPES; otherwise the result is `nil'." | |
115 | `(skip-until ,(parser-scanner context) | |
116 | (list ,@token-types) | |
117 | :keep-end ,(if keep-end-p keep-end | |
118 | (> (length token-types) 1)))) | |
119 | ||
33b5686f | 120 | (export 'error) |
048d0b2d | 121 | (defparse error (:context (context token-scanner-context) |
450a4be6 | 122 | (&key ignore-unconsumed force-progress) |
012554e1 | 123 | sub &optional (recover t)) |
048d0b2d MW |
124 | "Try to parse SUB; if it fails then report an error, and parse RECOVER. |
125 | ||
126 | This is the main way to recover from errors and continue parsing. Even | |
127 | then, it's not especially brilliant. | |
128 | ||
129 | If the SUB parser succeeds then just propagate its result: it's like we | |
130 | were never here. Otherwise, try to recover in a sensible way so we can | |
131 | continue parsing. The details of this recovery are subject to change, but | |
132 | the final action is generally to invoke the RECOVER parser and return its | |
012554e1 MW |
133 | result. |
134 | ||
135 | If IGNORE-UNCONSUMED evaluates non-nil, then just propagate a failure of | |
136 | SUB if it didn't consume input. (This makes it suitable for use where the | |
137 | parser containing `error' might be optional.)" | |
048d0b2d MW |
138 | `(parse-error-recover ,(parser-scanner context) |
139 | (parser () ,sub) | |
012554e1 | 140 | (parser () ,recover) |
450a4be6 MW |
141 | :ignore-unconsumed ,ignore-unconsumed |
142 | :force-progress ,force-progress)) | |
048d0b2d | 143 | |
ae7a3c8f MW |
144 | (export 'must) |
145 | (defparse must (:context (context token-scanner-context) | |
146 | sub &optional default) | |
147 | "Try to parse SUB; if it fails, report an error, and return DEFAULT. | |
148 | ||
149 | This parser can't actually fail." | |
150 | `(parse (error () ,sub (t ,default)))) | |
151 | ||
dea4d055 | 152 | ;;;-------------------------------------------------------------------------- |
239fa5bd MW |
153 | ;;; Lexical analysis utilities. |
154 | ||
33b5686f | 155 | (export 'scan-comment) |
239fa5bd MW |
156 | (defun scan-comment (char-scanner) |
157 | "Scan a comment (either `/* ... */' or `// ...') from CHAR-SCANNER. | |
158 | ||
159 | The result isn't interesting." | |
160 | (with-parser-context (character-scanner-context :scanner char-scanner) | |
e046c3f6 MW |
161 | (let ((start (file-location char-scanner))) |
162 | (parse (or (and "/*" | |
163 | (lisp (let ((state nil)) | |
164 | (loop (cond ((scanner-at-eof-p char-scanner) | |
165 | (lexer-error char-scanner | |
166 | (list "*/")) | |
167 | (info-with-location | |
168 | start "Comment started here") | |
169 | (return (values nil t t))) | |
170 | ((char= (scanner-current-char | |
171 | char-scanner) | |
172 | #\*) | |
173 | (setf state '*) | |
174 | (scanner-step char-scanner)) | |
175 | ((and (eq state '*) | |
176 | (char= (scanner-current-char | |
177 | char-scanner) | |
178 | #\/)) | |
179 | (scanner-step char-scanner) | |
180 | (return (values nil t t))) | |
181 | (t | |
182 | (setf state nil) | |
183 | (scanner-step char-scanner))))))) | |
184 | (and "//" | |
185 | (skip-many () (not #\newline)) | |
186 | (? #\newline))))))) | |
dea4d055 MW |
187 | |
188 | ;;;----- That's all, folks -------------------------------------------------- |