More efficient string switcher.

1 files changed, 77 insertions, 0 deletions

diff --git a/codegen.py b/codegen.py
new file mode 100644
index 0000000..2aff635
--- /dev/null
+++ b/codegen.py
@@ -0,0 +1,77 @@
+##########################################################################
+#
+# Copyright 2010 VMware, Inc.
+# All Rights Reserved.
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+#
+##########################################################################/
+
+
+def _string_switch(var, prefix, suffixes, case, default):
+    index = len(prefix)
+    indent = '    '*(index + 1)
+
+    if len(suffixes) == 1:
+        suffix = suffixes[0]
+        chars = list(suffix) + ["\\0"]
+        predicates = ['%s[%u] == \'%s\'' % (var, index + i, chars[i]) for i in range(len(chars))]
+        print indent + 'if (%s) {' % (' && '.join(predicates),)
+        value = prefix + suffix
+        print indent + '    // %s' % value
+        case(value)
+        print indent + '}'
+        if default is not None:
+            print indent + 'else {'
+            default()
+            print indent + '}'
+        return
+
+    print indent + 'switch (%s[%u]) {' % (var, index)
+    if "" in suffixes:
+        print indent + 'case \'\\0\':'
+        print indent + '    // %s' % prefix
+        case(prefix)
+        print indent + '    break;'
+
+    chars = [suffix[0] for suffix in suffixes if suffix]
+    chars = list(set(chars))
+    chars.sort()
+
+    for char in chars:
+        print indent + 'case \'%c\':' % (char)
+        new_prefix = prefix + char
+        new_suffixes = [suffix[1:] for suffix in suffixes if suffix.startswith(char)]
+        _string_switch(var, new_prefix, new_suffixes, case, default)
+        print indent + '    break;'
+    if default is not None:
+        print indent + 'default:'
+        default()
+        print indent + '    break;'
+    print indent + '}'
+
+
+def _noop(*args, **kwargs):
+    pass
+
+
+def string_switch(var, values, case=_noop, default=None):
+    values = list(values)
+    values.sort()
+    _string_switch(var, '', values, case, default)