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+;;; guile-syntax-highlight -- General-purpose syntax highlighter
+;;; Copyright © 2015 David Thompson <davet@gnu.org>
+;;;
+;;; Guile-syntax-highlight is free software; you can redistribute it
+;;; and/or modify it under the terms of the GNU Lesser General Public
+;;; License as published by the Free Software Foundation; either
+;;; version 3 of the License, or (at your option) any later version.
+;;;
+;;; Guile-syntax-highlight is distributed in the hope that it will be
+;;; useful, but WITHOUT ANY WARRANTY; without even the implied
+;;; warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+;;; See the GNU Lesser General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Lesser General Public
+;;; License along with guile-syntax-highlight.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+;;
+;; General-purpose syntax highlighting framework.
+;;
+;;; Code:
+
+(define-module (syntax-highlight)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-41)
+  #:export (highlight
+            highlights->sxml))
+
+(define (string->stream str)
+  "Convert the string STR into a stream of characters."
+  (stream-map (lambda (i)
+                (string-ref str i))
+              (stream-range 0 (string-length str))))
+
+(define* (highlight highlighter #:optional (stream (current-input-port)))
+  "Apply HIGHLIGHTER, a syntax highlighting procedure, to STREAM.
+STREAM may be an open port, string, or SRFI-41 character stream.  If
+STREAM is not specified, characters are read from the current input
+port."
+  (let-values (((result stream)
+                (highlighter (cond
+                              ((port? stream)
+                               (port->stream stream))
+                              ((string? stream)
+                               (string->stream stream))
+                              ((stream? stream)
+                               stream)
+                              (else
+                               (error "Cannot convert to stream: " stream))))))
+    result))
+
+(define (highlights->sxml highlights)
+  "Convert HIGHLIGHTS, a list of syntax highlighting expressions, into
+a list of SXML 'span' nodes.  Each 'span' node has a 'class' attribute
+corresponding to the highlighting tag name."
+  (define (tag->class tag)
+    (string-append "syntax-" (symbol->string tag)))
+
+  (map (match-lambda
+         ((? string? str) str)
+         ((tag text)
+          `(span (@ (class ,(tag->class tag))) ,text)))
+       highlights))