add some-system-path<->string functions to scheme/path

svn: r13065

collects/scheme/path.ss

@@ -6,7 +6,9 @@
          normalize-path
          filename-extension
          file-name-from-path
-         path-only)
+         path-only
+         some-system-path->string
+         string->some-system-path)
 
 (define (simple-form-path p)
   (unless (path-string? p)
@@ -168,3 +170,18 @@
          [name (and name (path->bytes name))])
     (cond [(and name (regexp-match #rx#"[.]([^.]+)$" name)) => cadr]
           [else #f])))
+
+(define (some-system-path->string path)
+  (unless (path-for-some-system? path)
+    (raise-type-error 'some-system-path->string "path (for any platform)" path))
+  (bytes->string/utf-8 (path->bytes path)))
+
+(define (string->some-system-path path kind)
+  (unless (string? path)
+    (raise-type-error 'string->some-system-path "string" path))
+  (unless (or (eq? kind 'unix)
+              (eq? kind 'windows))
+    (raise-type-error 'string->some-system-path "'unix or 'windows" kind))
+  (bytes->path (string->bytes/utf-8 path) kind))
+
+

collects/scribblings/reference/paths.scrbl

@@ -65,7 +65,9 @@ Beware that the current locale might not encode every string, in which
 case @scheme[string->path] can produce the same path for different
 @scheme[str]s. See also @scheme[string->path-element], which should be
 used instead of @scheme[string->path] when a string represents a
-single path element.}
+single path element.
+
+See also @scheme[string->some-system-path].}
 
 @defproc[(bytes->path [bstr bytes?]
                       [type (or/c 'unix 'windows) (system-path-convention-type)]) 
@@ -97,7 +99,9 @@ Furthermore, for display and sorting based on individual path elements
 (such as pathless file names), use @scheme[path-element->string],
 instead, to avoid special encodings use to represent some relative
 paths. See @secref["windowspaths"] for specific information about
-the conversion of Windows paths.}
+the conversion of Windows paths.
+
+See also @scheme[some-system-path->string].}
 
 @defproc[(path->bytes [path path?]) bytes?]{
 
@@ -560,6 +564,27 @@ Returns @scheme[(simplify-path (path->complete-path path))], which
 ensures that the result is a complete path containing no up- or
 same-directory indicators.}
 
+@defproc[(some-system-path->string [path path-for-some-system?])
+         string?]{
+
+Converts @scheme[path] to a string using a UTF-8 encoding of the
+path's bytes.
+
+Use this function when working with paths for a different system
+(whose encoding of pathnames might be unrelated to the current
+locale's encoding) and when starting and ending with strings.}
+
+@defproc[(string->some-system-path [str string?]
+                                   [kind (or/c 'unix 'windows)])
+         path-for-some-system?]{
+
+Converts @scheme[str] to a @scheme[kind] path using a UTF-8 encoding
+of the path's bytes.
+
+Use this function when working with paths for a different system
+(whose encoding of pathnames might be unrelated to the current
+locale's encoding) and when starting and ending with strings.}
+
 @;------------------------------------------------------------------------
 @include-section["unix-paths.scrbl"]
 @include-section["windows-paths.scrbl"]

collects/tests/mzscheme/pathlib.ss

@@ -66,4 +66,14 @@
 
 ;; ----------------------------------------
 
+(test "a" some-system-path->string (string->path "a"))
+(test "a" some-system-path->string (bytes->path #"a" 'unix))
+(test "a" some-system-path->string (bytes->path #"a" 'windows))
+(test #t path-for-some-system? (string->some-system-path "a" 'unix))
+(test #t path-for-some-system? (string->some-system-path "a" 'windows))
+(test "a" some-system-path->string (string->some-system-path "a" 'unix))
+(test "a" some-system-path->string (string->some-system-path "a" 'windows))
+
+;; ----------------------------------------
+
 (report-errs)