userdiff: extend Scheme support to cover other Lisp dialects

Documentation/gitattributes.adoc

@@ -912,6 +912,7 @@ patterns are available:
 - `rust` suitable for source code in the Rust language.
 
 - `scheme` suitable for source code in the Scheme language.
+Also handles Emacs Lisp, Common Lisp, and other dialects.
 
 - `tex` suitable for source code for LaTeX documents.
 

t/t4018/scheme-lisp-defun-a

@@ -0,0 +1,4 @@
+(defun some-func (x y z) RIGHT
+  (let ((a x)
+        (b y))
+        (ChangeMe a b)))

t/t4018/scheme-lisp-defun-b

@@ -0,0 +1,4 @@
+(macrolet ((foo (x) `(bar ,x)))
+  (defun mumble (x) ; RIGHT
+    (when (> x 0)
+      (foo x)))) ; ChangeMe

t/t4018/scheme-lisp-eval-when

@@ -0,0 +1,4 @@
+(eval-when (:compile-toplevel :load-toplevel :execute)  ; RIGHT
+  (set-macro-character #\?
+		       (lambda (stream char)
+			 `(make-pattern-variable ,(read stream)))))  ; ChangeMe

t/t4018/scheme-module-b

@@ -0,0 +1,6 @@
+(module A
+  (export with-display-exception)
+  (extern (display-exception display-exception))
+  (def (with-display-exception thunk) RIGHT
+    (with-catch (lambda (e) (display-exception e (current-error-port)) e)
+      thunk ChangeMe)))

userdiff.c

@@ -344,14 +344,24 @@ PATTERNS("rust",
 	 "|[0-9][0-9_a-fA-Fiosuxz]*(\\.([0-9]*[eE][+-]?)?[0-9_fF]*)?"
 	 "|[-+*\\/<>%&^|=!:]=|<<=?|>>=?|&&|\\|\\||->|=>|\\.{2}=|\\.{3}|::"),
 PATTERNS("scheme",
-	 "^[\t ]*(\\(((define|def(struct|syntax|class|method|rules|record|proto|alias)?)[-*/ \t]|(library|module|struct|class)[*+ \t]).*)$",
 	 /*
-	  * R7RS valid identifiers include any sequence enclosed
-	  * within vertical lines having no backslashes
+	  * An unindented opening parenthesis identifies a top-level
+	  * expression in all Lisp dialects.
 	  */
-	 "\\|([^\\\\]*)\\|"
-	 /* All other words should be delimited by spaces or parentheses */
-	 "|([^][)(}{[ \t])+"),
+	 "^(\\(.*)$\n"
+	 /* For Scheme: a possibly indented left paren followed by a keyword. */
+	 "^[\t ]*(\\(((define|def(struct|syntax|class|method|rules|record|proto|alias)?)[-*/ \t]|(library|module|struct|class)[*+ \t]).*)$\n"
+	 /*
+	  * For all Lisp dialects: a slightly indented line starting with "(def".
+	  */
+	 "^ {1,2}(\\([Dd][Ee][Ff].*)$",
+	 /*
+	  * The union of R7RS and Common Lisp symbol syntax: allows arbitrary
+	  * strings between vertical bars, including any escaped characters.
+	  */
+	 "\\|([^\\\\]|\\\\.)*\\|"
+	 /* All other words should be delimited by spaces or parentheses. */
+	 "|([^][)(}{ \t])+"),
 PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",
 	 "\\\\[a-zA-Z@]+|\\\\.|([a-zA-Z0-9]|[^\x01-\x7f])+"),
 { .name = "default", .binary = -1 },