io, system: disallow if-does-not-exist: #f for file streams

fixes dylan-lang#1358

documentation/source/library-reference/io/streams.rst

@@ -1233,8 +1233,10 @@ are exported from the *streams* module.
    :keyword if-exists: One of :drm:`#f`, ``#"new-version"``,
      ``#"overwrite"``, ``#"replace"``, ``#"append"``, ``#"truncate"``,
      ``#"signal"``. Default value: :drm:`#f`.
-   :keyword if-does-not-exist: One of :drm:`#f`, ``#"signal"``, or
-     ``#"create"``. Default value: depends on the value of ``direction:``.
+   :keyword if-does-not-exist: Either ``#"signal"`` or ``#"create"``.
+      The default (and only valid value) for direction ``#"input"`` is
+      ``#"signal"``.  The default for direction ``#"output"`` and
+      ``#"input-output"`` is ``#"create"``.
    :keyword asynchronous?: If :drm:`#t`, all writes on this stream are
      performed asynchronously. Default value::drm:`#f`.
 

documentation/source/library-reference/system/file-system.rst

@@ -216,7 +216,9 @@ module.
 The :drm:`make` method on :class:`<file-stream>` does not create
 direct instances of :class:`<file-stream>`, but instead an instance of
 a subclass determined by :gf:`type-for-file-stream`. See
-`make`_ and `Options when creating file streams`_ below.
+`make`_ and :ref:`file-stream-options` below.
+
+.. _file-stream-options:
 
 Options when creating file streams
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -257,9 +259,9 @@ the file named by *filename* already exists. The options are:
 The ``if-does-not-exist:`` init-keyword allows you to specify an action to
 take if the file named by *filename* does not exist. The options are:
 
-- :drm:`#f` No action.
-- ``#"signal"`` Signal a :class:`<file-does-not-exist-error>` condition. This is
-  the default when the stream's direction is ``#"input"``.
+- ``#"signal"`` Signal a :class:`<file-does-not-exist-error>` condition. This
+  is the default (and the only valid value) when the stream's direction is
+  ``#"input"``.
 - ``#"create"`` Create a new zero-length file. This is the default when
   the stream's direction is ``#"output"`` or ``#"input-output"``.
 
@@ -933,8 +935,10 @@ File-System module.
    :parameter #key if-exists: One of :drm:`#f`, ``#"new-version"``,
      ``#"overwrite"``, ``#"replace"``, ``#"append"``, ``#"truncate"``,
      ``#"signal"``. Default value: :drm:`#f`.
-   :parameter #key if-does-not-exist: One of :drm:`#f`, ``#"signal"``, or
-     ``#"create"``. Default value: depends on the value of *direction*.
+   :parameter #key if-does-not-exist: Either ``#"signal"`` or ``#"create"``.
+      The default (and only valid value) for direction ``#"input"`` is
+      ``#"signal"``.  The default for direction ``#"output"`` and
+      ``#"input-output"`` is ``#"create"``.
    :parameter #key buffer-size: An instance of :drm:`<integer>`.
    :parameter #key element-type: One of :type:`<byte-character>`,
      :type:`<unicode-character>`, or :type:`<byte>`, or :drm:`#f`.
@@ -960,7 +964,7 @@ File-System module.
      The *if-exists* and *if-does-not-exist* init-keywords specify
      actions to take if the file named by *filename* does or does not
      already exist when the stream is created. These init-keywords are
-     discussed in more detail in `Options when creating file streams`_.
+     discussed in more detail in :ref:`file-stream-options`.
 
      The *buffer-size* init-keyword can be used to suggest the size of
      a stream's buffer. See :class:`<buffered-stream>`.
@@ -971,7 +975,7 @@ File-System module.
      treated as a single database record. This init-keyword defaults to
      something useful, potentially based on the properties of the file;
      :type:`<byte-character>` and :type:`<unicode-character>` are likely choices.
-     See `Options when creating file streams`_.
+     See :ref:`file-stream-options`.
 
    :seealso:
 

sources/io/streams/file-stream.dylan

@@ -14,7 +14,7 @@ end class <external-file-accessor>;
 
 /// File stream classes
 
-// File streams basically to not inherit any significant methods from
+// File streams basically do not inherit any significant methods from
 // <single-buffered-stream> or <positionable-stream>, only protocol.
 // This is because they use power of two sized buffers which are aligned with
 // disk segments.  <single-buffered-stream> uses non-aligned buffers

sources/system/file-system/unix-file-accessor.dylan

@@ -19,10 +19,22 @@ define constant $file_create_permissions
 define sideways method accessor-open
     (accessor :: <native-file-accessor>, locator :: <pathname>,
      #rest keywords,
-     #key direction = #"input", if-exists, if-does-not-exist,
-       file-position: initial-file-position = #f, // :: false-or(<integer>)?
-       file-size: initial-file-size = #f, // :: false-or(<integer>)?
+     #key direction = #"input", if-exists,
+          if-does-not-exist = unsupplied(),
+          file-position: initial-file-position, // :: false-or(<integer>)?
+          file-size: initial-file-size, // :: false-or(<integer>)?
      #all-keys) => ()
+  local
+    method check-if-does-not-exist (valid-options, default)
+      if (unsupplied?(if-does-not-exist))
+        default
+      elseif (~member?(if-does-not-exist, valid-options))
+        error("if-does-not-exist: %= is not valid for direction: %=",
+              if-does-not-exist, direction);
+      else
+        if-does-not-exist
+      end;
+    end;
   block (return)
     let locator = expand-pathname(locator);
     let pathstring = as(<byte-string>, locator);
@@ -32,15 +44,15 @@ define sideways method accessor-open
           #"input" =>
             values($O_RDONLY,
                    #"overwrite",
-                   (if-does-not-exist | #"signal"));
+                   check-if-does-not-exist(#[#"signal"], #"signal"));
           #"output" =>
             values(logior($O_WRONLY, $O_SYNC),
                    (if-exists | #"new-version"),
-                   (if-does-not-exist | #"create"));
+                   check-if-does-not-exist(#[#"signal", #"create"], #"create"));
           #"input-output" =>
             values(logior($O_RDWR, $O_SYNC),
                    (if-exists | #"overwrite"),
-                   (if-does-not-exist | #"create"));
+                   check-if-does-not-exist(#[#"signal", #"create"], #"create"));
         end;
     let mode-code
       = if (exists)

sources/system/file-system/win32-file-accessor.dylan

@@ -31,15 +31,28 @@ end function win32-file-error;
 define sideways method accessor-open
     (accessor :: <native-file-accessor>, locator :: <pathname>,
      #rest keywords,
-     #key direction = #"input", if-exists, if-does-not-exist,
-       file-descriptor: initial-file-handle = #f, // :: false-or(<machine-word>)
-       file-position: initial-file-position = #f, // :: false-or(<integer>)?
-       file-size: initial-file-size = #f, // :: false-or(<integer>)?
-       overlapped? :: <boolean> = #f,
-       share? :: <boolean> = #t, // only shared access allowed in the past
-       share-mode :: one-of(#"default", #"exclusive", #"share-read",
-                            #"share-write", #"share-read-write") = #"default",
-     #all-keys) => ();
+     #key direction = #"input",
+          if-exists,
+          if-does-not-exist = unsupplied(),
+          file-descriptor: initial-file-handle, // :: false-or(<machine-word>)
+          file-position: initial-file-position, // :: false-or(<integer>)?
+          file-size: initial-file-size, // :: false-or(<integer>)?
+          overlapped? :: <boolean>,
+          share? :: <boolean> = #t, // only shared access allowed in the past
+          share-mode :: one-of(#"default", #"exclusive", #"share-read",
+                               #"share-write", #"share-read-write") = #"default",
+     #all-keys) => ()
+  local
+    method check-if-does-not-exist (valid-options, default)
+      if (unsupplied?(if-does-not-exist))
+        default
+      elseif (~member?(if-does-not-exist, valid-options))
+        error("if-does-not-exist: %= is not valid for direction: %=",
+              if-does-not-exist, direction);
+      else
+        if-does-not-exist
+      end;
+    end;
   block (return)
     if (initial-file-position | initial-file-size)
       error("Cannot create a file accessor which specifies either"
@@ -49,13 +62,13 @@ define sideways method accessor-open
     select (direction)
       #"input" =>
         if-exists := #"overwrite";
-        if-does-not-exist := if-does-not-exist | #"signal";
+        if-does-not-exist := check-if-does-not-exist(#[#"signal"], #"signal");
       #"output" =>
         if-exists := if-exists | #"new-version";
-        if-does-not-exist := if-does-not-exist | #"create";
+        if-does-not-exist := check-if-does-not-exist(#[#"create", #"signal"], #"create");
       #"input-output" =>
         if-exists := if-exists | #"overwrite";
-        if-does-not-exist := if-does-not-exist | #"create";
+        if-does-not-exist := check-if-does-not-exist(#[#"create", #"signal"], #"create");
     end;
     let fdwAccess
       = select (direction)

sources/system/tests/file-system.dylan

@@ -180,8 +180,62 @@ end test;
 
 /// Macro tests
 
-define test test-with-open-file-test ()
-  // ---*** Fill this in.
+// For direction: #"input", #"signal" is the only valid option.
+define test test-with-open-file/if-does-not-exist/input ()
+  assert-signals(<file-does-not-exist-error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "input1"),
+                                 direction: #"input",
+                                 if-does-not-exist: #"signal")
+                   assert-true(#f, "input1 body should not be executed");
+                 end);
+  assert-signals(<error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "input2"),
+                                 direction: #"input",
+                                 if-does-not-exist: #"create")
+                   assert-true(#f, "input2 body should not be executed");
+                 end);
+  assert-signals(<error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "input3"),
+                                 direction: #"input",
+                                 if-does-not-exist: #f) // not a valid option anymore
+                   assert-true(#f, "input3 body should not be executed");
+                 end);
+  assert-signals(<error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "input4"),
+                                 direction: #"input",
+                                 if-does-not-exist: #"foo") // not a valid option
+                   assert-true(#f, "input4 body should not be executed");
+                 end);
+  // if-does-not-exist not specified.
+  assert-signals(<error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "input5"),
+                                 direction: #"input")
+                   assert-true(#f, "input5 body should not be executed");
+                 end);
+end test;
+
+// For direction: #"output", #"create" (default) and #"signal" are valid.
+define test test-with-open-file/if-does-not-exist/output ()
+  assert-signals(<file-does-not-exist-error>,
+                 with-open-file (stream = file-locator(test-temp-directory(), "output1"),
+                                 direction: #"output",
+                                 if-does-not-exist: #"signal")
+                   assert-true(#f, "output1 body should not be executed");
+                 end);
+  let output2 = file-locator(test-temp-directory(), "output2");
+  with-open-file (stream = output2 ,
+                  direction: #"output",
+                  if-does-not-exist: #"create")
+    write(stream, "output2");
+  end;
+  assert-equal("output2", with-open-file (stream = output2) read-to-end(stream) end);
+
+  // Same as above but if-does-not-exist: is not specified.
+  let output3 = file-locator(test-temp-directory(), "abc");
+  with-open-file (stream = output3 , direction: #"output")
+    write(stream, "output3");
+  end;
+  assert-equal("abc", with-open-file (stream = output3) read-to-end(stream) end);
 end test;