diff options
| -rw-r--r-- | src/guile/skribilo/package/diff.scm | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/src/guile/skribilo/package/diff.scm b/src/guile/skribilo/package/diff.scm index 3aeed08..12eedb3 100644 --- a/src/guile/skribilo/package/diff.scm +++ b/src/guile/skribilo/package/diff.scm @@ -21,6 +21,7 @@ (define-module (skribilo package diff) :use-module (differ) :use-module (srfi srfi-1) + :use-module (srfi srfi-14) :use-module (srfi srfi-39) :use-module (ice-9 optargs) @@ -197,19 +198,45 @@ ;; Return a list (actually an AST) denoting the differences between STR1 ;; and STR2. The returned text is actually that of STR2 augmented with ;; `insertion', `deletion', `replacement', and `unchanged' markup. + + (define (space-preserving-substring str start end) + ;; Return the substring of STR, possibly inserting unbreakable spaces at + ;; the beginning/end if STR starts/ends in whitespaces. + (let ((len (- end start))) + (if (> len 0) + (let* ((lead (string-ref str start)) + (lead* (if (char-set-contains? char-set:whitespace + lead) + (~) + (string lead)))) + (if (> len 1) + (let* ((trail (string-ref str (- end 1))) + (trail* (if (char-set-contains? char-set:whitespace + trail) + (~) + (string trail)))) + (list lead* (substring str (+ start 1) (- end 1)) + trail*)) + (list lead* (substring str (+ start 1) end)))) + ""))) + (reverse! (fold (lambda (edit result) (let ((start (cadr edit)) (end (+ 1 (caddr edit)))) (cons (case (car edit) ((insertion) - (insertion (substring str2 start end))) + (insertion (space-preserving-substring str2 start + end))) ((deletion) - (deletion (substring str1 start end))) + (deletion (space-preserving-substring str1 start + end))) ((replacement) - (replacement (substring str2 start end))) + (replacement (space-preserving-substring str2 start + end))) ((unchanged) - (unchanged (substring str2 start end)))) + (unchanged (space-preserving-substring str2 start + end)))) result))) '() (string-diff-sequences str1 str2)))) |