meson: add script to print the options before configuring a builddir

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>

bin/meson-options.py

@@ -0,0 +1,63 @@
+#!/usr/bin/env python3
+
+from os import get_terminal_size
+from textwrap import wrap
+from mesonbuild import coredata
+from mesonbuild import optinterpreter
+
+(COLUMNS, _) = get_terminal_size()
+
+def describe_option(option_name: str, option_default_value: str,
+                    option_type: str, option_message: str) -> None:
+    print('name:    ' + option_name)
+    print('default: ' + option_default_value)
+    print('type:    ' + option_type)
+    for line in wrap(option_message, width=COLUMNS - 9):
+        print('         ' + line)
+    print('---')
+
+oi = optinterpreter.OptionInterpreter('')
+oi.process('meson_options.txt')
+
+for (name, value) in oi.options.items():
+    if isinstance(value, coredata.UserStringOption):
+        describe_option(name,
+                        value.value,
+                        'string',
+                        "You can type what you want, but make sure it makes sense")
+    elif isinstance(value, coredata.UserBooleanOption):
+        describe_option(name,
+                        'true' if value.value else 'false',
+                        'boolean',
+                        "You can set it to 'true' or 'false'")
+    elif isinstance(value, coredata.UserIntegerOption):
+        describe_option(name,
+                        str(value.value),
+                        'integer',
+                        "You can set it to any integer value between '{}' and '{}'".format(value.min_value, value.max_value))
+    elif isinstance(value, coredata.UserUmaskOption):
+        describe_option(name,
+                        str(value.value),
+                        'umask',
+                        "You can set it to 'preserve' or a value between '0000' and '0777'")
+    elif isinstance(value, coredata.UserComboOption):
+        choices = '[' + ', '.join(["'" + v + "'" for v in value.choices]) + ']'
+        describe_option(name,
+                        value.value,
+                        'combo',
+                        "You can set it to any one of those values: " + choices)
+    elif isinstance(value, coredata.UserArrayOption):
+        choices = '[' + ', '.join(["'" + v + "'" for v in value.choices]) + ']'
+        value = '[' + ', '.join(["'" + v + "'" for v in value.value]) + ']'
+        describe_option(name,
+                        value,
+                        'array',
+                        "You can set it to one or more of those values: " + choices)
+    elif isinstance(value, coredata.UserFeatureOption):
+        describe_option(name,
+                        value.value,
+                        'feature',
+                        "You can set it to 'auto', 'enabled', or 'disabled'")
+    else:
+        print(name + ' is an option of a type unknown to this script')
+        print('---')

docs/meson.html

@@ -58,7 +58,9 @@ and your local settings.
 <p>
 Meson does not currently support listing options before configure a build
 directory, but this feature is being discussed upstream.
-For now, the only way to see what options exist is to look at the
+For now, we have a <code>bin/meson-options.py</code> script that prints
+the options for you.
+If that script doesn't work for some reason, you can always look in the
 <code>meson_options.txt</code> file at the root of the project.
 </p>