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authorDaniel Kraft <d@domob.eu>2009-08-26 21:03:06 +0200
committerDaniel Kraft <d@domob.eu>2009-08-26 21:03:06 +0200
commitddb4364b1a1635fce0b1d2eaa7d50a951c6c4dfc (patch)
tree54baf10e6778bfbc41eba35acc868171164768ec
parent5b1ee3bef15380745f6c2fc598768d9f3a46e85e (diff)
downloadguile-ddb4364b1a1635fce0b1d2eaa7d50a951c6c4dfc.tar.gz
get-lexer/1 for elisp that finishes after the first full expression is read.
* module/language/elisp/lexer.scm: Add get-lexer/1. * test-suite/tests/elisp-reader.test: Test lexer/1.
-rw-r--r--module/language/elisp/lexer.scm27
-rw-r--r--test-suite/tests/elisp-reader.test24
2 files changed, 41 insertions, 10 deletions
diff --git a/module/language/elisp/lexer.scm b/module/language/elisp/lexer.scm
index 3dbce8676..05df03d89 100644
--- a/module/language/elisp/lexer.scm
+++ b/module/language/elisp/lexer.scm
@@ -21,11 +21,11 @@
(define-module (language elisp lexer)
#:use-module (ice-9 regex)
- #:export (get-lexer))
+ #:export (get-lexer get-lexer/1))
; This is the lexical analyzer for the elisp reader. It is hand-written
-; instead of using some generator because I think that's most viable in this
-; case and easy enough.
+; instead of using some generator. I think this is the best solution
+; because of all that fancy escape sequence handling and the like.
; Characters are handled internally as integers representing their
; code value. This is necessary because elisp allows a lot of fancy modifiers
@@ -334,3 +334,24 @@
(define (get-lexer port)
(lambda ()
(lex port)))
+
+
+; Build a special lexer that will only read enough for one expression and then
+; always return end-of-input.
+
+(define (get-lexer/1 port)
+ (let ((lex (get-lexer port))
+ (finished #f)
+ (paren-level 0))
+ (lambda ()
+ (if finished
+ '*eoi*
+ (let ((next (lex)))
+ (case (car next)
+ ((paren-open square-open)
+ (set! paren-level (1+ paren-level)))
+ ((paren-close square-close)
+ (set! paren-level (1- paren-level))))
+ (if (<= paren-level 0)
+ (set! finished #t))
+ next)))))
diff --git a/test-suite/tests/elisp-reader.test b/test-suite/tests/elisp-reader.test
index 15d5344b2..365f578ce 100644
--- a/test-suite/tests/elisp-reader.test
+++ b/test-suite/tests/elisp-reader.test
@@ -31,13 +31,15 @@
(define (get-string-lexer str)
(call-with-input-string str get-lexer))
+(define (lex-all lexer)
+ (let iterate ((result '()))
+ (let ((token (lexer)))
+ (if (eq? token '*eoi*)
+ (reverse result)
+ (iterate (cons token result))))))
+
(define (lex-string str)
- (let ((lexer (get-string-lexer str)))
- (let iterate ((result '()))
- (let ((token (lexer)))
- (if (eq? token '*eoi*)
- (reverse result)
- (iterate (cons token result)))))))
+ (lex-all (get-string-lexer str)))
(with-test-prefix "Lexer"
@@ -113,4 +115,12 @@ test\"ab\"\\ abcd
`(,(+ (expt 2 26) (char->integer #\[))
,(+ (expt 2 27) (expt 2 25) (char->integer #\Z))
,(- (char->integer #\X) (char->integer #\@))
- ,(+ (expt 2 22) (expt 2 23) (expt 2 24) 32)))))
+ ,(+ (expt 2 22) (expt 2 23) (expt 2 24) 32))))
+
+ (let* ((lex1-string "((1 2) [2 [3]] 5)")
+ (lexer (call-with-input-string (string-append lex1-string " 1 2")
+ get-lexer/1)))
+ (pass-if "lexer/1"
+ (and (equal? (lex-all lexer) (lex-string lex1-string))
+ (eq? (lexer) '*eoi*)
+ (eq? (lexer) '*eoi*)))))