1 files changed, 94 insertions, 0 deletions
diff --git a/misc/ninja_syntax.py b/misc/ninja_syntax.py
new file mode 100644
index 0000000..7fa4bf1
--- /dev/null
+++ b/misc/ninja_syntax.py
@@ -0,0 +1,94 @@
+#!/usr/bin/python
+
+"""Python module for generating .ninja files.
+
+Note that this is emphatically not a required piece of Ninja; it's
+just a helpful utility for build-file-generation systems that already
+use Python.
+"""
+
+import textwrap
+
+class Writer(object):
+    def __init__(self, output, width=78):
+        self.output = output
+        self.width = width
+
+    def newline(self):
+        self.output.write('\n')
+
+    def comment(self, text):
+        for line in textwrap.wrap(text, self.width - 2):
+            self.output.write('# ' + line + '\n')
+
+    def variable(self, key, value, indent=0):
+        self._line('%s = %s' % (key, value), indent)
+
+    def rule(self, name, command, description=None, depfile=None):
+        self._line('rule %s' % name)
+        self.variable('command', command, indent=1)
+        if description:
+            self.variable('description', description, indent=1)
+        if depfile:
+            self.variable('depfile', depfile, indent=1)
+
+    def build(self, outputs, rule, inputs=None, implicit=None, order_only=None,
+              variables=None):
+        outputs = self._as_list(outputs)
+        all_inputs = self._as_list(inputs)[:]
+
+        if implicit:
+            all_inputs.append('|')
+            all_inputs.extend(self._as_list(implicit))
+        if order_only:
+            all_inputs.append('||')
+            all_inputs.extend(self._as_list(order_only))
+
+        self._line('build %s: %s %s' % (' '.join(outputs),
+                                        rule,
+                                        ' '.join(all_inputs)))
+
+        if variables:
+            for key, val in variables:
+                self.variable(key, val, indent=1)
+
+        return outputs
+
+    def _line(self, text, indent=0):
+        """Write 'text' word-wrapped at self.width characters."""
+        leading_space = '  ' * indent
+        while len(text) > self.width:
+            # The text is too wide; wrap if possible.
+
+            # Find the rightmost space that would obey our width constraint.
+            available_space = self.width - len(leading_space) - len(' $')
+            space = text.rfind(' ', 0, available_space)
+            if space < 0:
+                # No such space; just use the first space we can find.
+                space = text.find(' ', available_space)
+            if space < 0:
+                # Give up on breaking.
+                break
+
+            self.output.write(leading_space + text[0:space] + ' $\n')
+            text = text[space+1:]
+
+            # Subsequent lines are continuations, so indent them.
+            leading_space = '  ' * (indent+2)
+
+        self.output.write(leading_space + text + '\n')
+
+    def _as_list(self, input):
+        if input is None:
+            return []
+        if isinstance(input, list):
+            return input
+        return [input]
+
+
+def escape(string):
+    """Escape a string such that it can be embedded into a Ninja file without
+    further interpretation."""
+    assert '\n' not in string, 'Ninja syntax does not allow newlines'
+    # We only have one special metacharacter: '$'.
+    return string.replace('$', '$$')