Add new array type option

This exposes the already existing UserStringArrayOption class through
the meson_options.txt. The intention is to provide a way for projects to
take list/array type arguments and validate that all of the elements in
that array are valid without using complex looping constructrs.

The Mesa project would like to use this feature for passing lists of
drivers to be be built.

docs/markdown/Build-options.md

@@ -16,9 +16,10 @@ Here is a simple option file.
 option('someoption', type : 'string', value : 'optval', description : 'An option')
 option('other_one', type : 'boolean', value : false)
 option('combo_opt', type : 'combo', choices : ['one', 'two', 'three'], value : 'three')
+option('array_opt', type : 'array', choices : ['one', 'two', 'three'], value : ['one', 'two'])
 ```
 
-This demonstrates the three basic option types and their usage. String
+This demonstrates the four basic option types and their usage. String
 option is just a free form string and a boolean option is,
 unsurprisingly, true or false. The combo option can have any value
 from the strings listed in argument `choices`. If `value` is not set,
@@ -29,6 +30,8 @@ name.
 
 These options are accessed in Meson code with the `get_option` function.
 
+The array type is new in 0.44.0
+
 ```meson
 optval = get_option('opt_name')
 ```

docs/markdown/snippets/option-array-type.md

@@ -0,0 +1,17 @@
+# An array type for user options
+
+Previously to have an option that took more than one value a string value would
+have to be created and split, but validating this was difficult. A new array type
+has been added to the meson_options.txt for this case. It works like a 'combo', but
+allows more than one option to be passed. When used on the command line (with -D),
+values are passed as a comma separated list.
+
+    ```meson
+    option('array_opt', type : 'array', choices : ['one', 'two', 'three'], value : 'one')
+    ```
+
+These can be overwritten on the command line,
+
+    ```meson
+    meson _build -Darray_opt=two,three
+    ```

mesonbuild/coredata.py

@@ -139,24 +139,37 @@ def validate_value(self, value):
 class UserStringArrayOption(UserOption):
     def __init__(self, name, description, value, **kwargs):
         super().__init__(name, description, kwargs.get('choices', []))
-        self.set_value(value)
-
-    def validate(self, value):
-        if isinstance(value, str):
-            if not value.startswith('['):
-                raise MesonException('Valuestring does not define an array: ' + value)
-            newvalue = ast.literal_eval(value)
+        self.set_value(value, user_input=False)
+
+    def validate(self, value, user_input):
+        # User input is for options defined on the command line (via -D
+        # options). Users should put their input in as a comma separated
+        # string, but for defining options in meson_options.txt the format
+        # should match that of a combo
+        if not user_input:
+            if isinstance(value, str):
+                if not value.startswith('['):
+                    raise MesonException('Valuestring does not define an array: ' + value)
+                newvalue = ast.literal_eval(value)
+            else:
+                newvalue = value
         else:
-            newvalue = value
+            assert isinstance(value, str)
+            newvalue = [v.strip() for v in value.split(',')]
         if not isinstance(newvalue, list):
             raise MesonException('"{0}" should be a string array, but it is not'.format(str(newvalue)))
         for i in newvalue:
             if not isinstance(i, str):
                 raise MesonException('String array element "{0}" is not a string.'.format(str(newvalue)))
+        if self.choices:
+            bad = [x for x in newvalue if x not in self.choices]
+            if bad:
+                raise MesonException('Options "{}" are not in allowed choices: "{}"'.format(
+                    ', '.join(bad), ', '.join(self.choices)))
         return newvalue
 
-    def set_value(self, newvalue):
-        self.value = self.validate(newvalue)
+    def set_value(self, newvalue, user_input=True):
+        self.value = self.validate(newvalue, user_input)
 
     def validate_value(self, value):
         self.validate(value)

mesonbuild/optinterpreter.py

@@ -84,9 +84,24 @@ def ComboParser(name, description, kwargs):
             raise OptionException('Combo choice elements must be strings.')
     return coredata.UserComboOption(name, description, choices, kwargs.get('value', choices[0]))
 
+def string_array_parser(name, description, kwargs):
+    if 'choices' not in kwargs:
+        raise OptionException('Array option missing "choices" keyword.')
+    choices = kwargs['choices']
+    if not isinstance(choices, list):
+        raise OptionException('Array choices must be an array.')
+    for i in choices:
+        if not isinstance(i, str):
+            raise OptionException('Array choice elements must be strings.')
+    value = kwargs.get('value', choices[0])
+    if not isinstance(value, list):
+        value = [value]
+    return coredata.UserStringArrayOption(name, description, value, choices=choices)
+
 option_types = {'string': StringParser,
                 'boolean': BooleanParser,
                 'combo': ComboParser,
+                'array': string_array_parser,
                 }
 
 class OptionInterpreter:

test cases/common/47 options/meson.build

@@ -12,6 +12,15 @@ if get_option('combo_opt') != 'combo'
   error('Incorrect value to combo option.')
 endif
 
+if get_option('array_opt') != ['one', 'two']
+  message(get_option('array_opt'))
+  error('Incorrect value for array option (default >1 element)')
+endif
+
+if get_option('array_opt2') != ['one']
+  error('Incorrect value for array option (default 1 element)')
+endif
+
 # If the default changes, update test cases/unit/13 reconfigure
 if get_option('b_lto') != false
   error('Incorrect value in base option.')

test cases/common/47 options/meson_options.txt

@@ -1,3 +1,5 @@
 option('testoption', type : 'string', value : 'optval', description : 'An option to do something')
 option('other_one', type : 'boolean', value : false)
 option('combo_opt', type : 'combo', choices : ['one', 'two', 'combo'], value : 'combo')
+option('array_opt', type : 'array', choices : ['one', 'two', 'three'], value : ['one', 'two'])
+option('array_opt2', type : 'array', choices : ['one', 'two', 'three'], value : 'one')