Implement variable typing (sync from OE)

This implementation consists of two components:

- Type creation python modules, whose job it is to construct objects of the
  defined type for a given variable in the metadata
- typecheck.bbclass, which iterates over all configuration variables with a
  type defined and uses oe.types to check the validity of the values

This gives us a few benefits:

- Automatic sanity checking of all configuration variables with a defined type
- Avoid duplicating the "how do I make use of the value of this variable"
  logic between its users.  For variables like PATH, this is simply a split(),
  for boolean variables, the duplication can result in confusing, or even
  mismatched semantics (is this 0/1, empty/nonempty, what?)
- Make it easier to create a configuration UI, as the type information could
  be used to provide a better interface than a text edit box (e.g checkbox for
  'boolean', dropdown for 'choice')

This functionality is entirely opt-in right now.  To enable the configuration
variable type checking, simply INHERIT += "typecheck".  Example of a failing
type check:

BAZ = "foo"
BAZ[type] = "boolean"

$ bitbake -p
FATAL: BAZ: Invalid boolean value 'foo'
$

Examples of leveraging oe.types in a python snippet:

PACKAGES[type] = "list"

python () {
    import oe.data
    for pkg in oe.data.typed_value("PACKAGES", d):
        bb.note("package: %s" % pkg)
}

LIBTOOL_HAS_SYSROOT = "yes"
LIBTOOL_HAS_SYSROOT[type] = "boolean"

python () {
    import oe.data
    assert(oe.data.typed_value("LIBTOOL_HAS_SYSROOT", d) == True)
}

Signed-off-by: Chris Larson <chris_larson@mentor.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/meta/lib/oe/types.py b/meta/lib/oe/types.py
new file mode 100644
index 0000000000..ea31cf4219
--- /dev/null
+++ b/meta/lib/oe/types.py
@@ -0,0 +1,104 @@
+import re
+
+class OEList(list):
+    """OpenEmbedded 'list' type
+
+    Acts as an ordinary list, but is constructed from a string value and a
+    separator (optional), and re-joins itself when converted to a string with
+    str().  Set the variable type flag to 'list' to use this type, and the
+    'separator' flag may be specified (defaulting to whitespace)."""
+
+    name = "list"
+
+    def __init__(self, value, separator = None):
+        if value is not None:
+            list.__init__(self, value.split(separator))
+        else:
+            list.__init__(self)
+
+        if separator is None:
+            self.separator = " "
+        else:
+            self.separator = separator
+
+    def __str__(self):
+        return self.separator.join(self)
+
+def choice(value, choices):
+    """OpenEmbedded 'choice' type
+
+    Acts as a multiple choice for the user.  To use this, set the variable
+    type flag to 'choice', and set the 'choices' flag to a space separated
+    list of valid values."""
+    if not isinstance(value, basestring):
+        raise TypeError("choice accepts a string, not '%s'" % type(value))
+
+    value = value.lower()
+    choices = choices.lower()
+    if value not in choices.split():
+        raise ValueError("Invalid choice '%s'.  Valid choices: %s" %
+                         (value, choices))
+    return value
+
+def regex(value, regexflags=None):
+    """OpenEmbedded 'regex' type
+
+    Acts as a regular expression, returning the pre-compiled regular
+    expression pattern object.  To use this type, set the variable type flag
+    to 'regex', and optionally, set the 'regexflags' type to a space separated
+    list of the flags to control the regular expression matching (e.g.
+    FOO[regexflags] += 'ignorecase').  See the python documentation on the
+    're' module for a list of valid flags."""
+
+    flagval = 0
+    if regexflags:
+        for flag in regexflags.split():
+            flag = flag.upper()
+            try:
+                flagval |= getattr(re, flag)
+            except AttributeError:
+                raise ValueError("Invalid regex flag '%s'" % flag)
+
+    try:
+        return re.compile(value, flagval)
+    except re.error, exc:
+        raise ValueError("Invalid regex value '%s': %s" %
+                         (value, exc.args[0]))
+
+def boolean(value):
+    """OpenEmbedded 'boolean' type
+
+    Valid values for true: 'yes', 'y', 'true', 't', '1'
+    Valid values for false: 'no', 'n', 'false', 'f', '0'
+    """
+
+    if not isinstance(value, basestring):
+        raise TypeError("boolean accepts a string, not '%s'" % type(value))
+
+    value = value.lower()
+    if value in ('yes', 'y', 'true', 't', '1'):
+        return True
+    elif value in ('no', 'n', 'false', 'f', '0'):
+        return False
+    raise ValueError("Invalid boolean value '%s'" % value)
+
+def integer(value, numberbase=10):
+    """OpenEmbedded 'integer' type
+
+    Defaults to base 10, but this can be specified using the optional
+    'numberbase' flag."""
+
+    return int(value, int(numberbase))
+
+_float = float
+def float(value, fromhex='false'):
+    """OpenEmbedded floating point type
+
+    To use this type, set the type flag to 'float', and optionally set the
+    'fromhex' flag to a true value (obeying the same rules as for the
+    'boolean' type) if the value is in base 16 rather than base 10."""
+
+    if boolean(fromhex):
+        return _float.fromhex(value)
+    else:
+        return _float(value)