tww/tools/ninja_syntax.py

# Copyright 2011 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""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 re
import textwrap


def escape_path(word):
    return word.replace("$ ", "$$ ").replace(" ", "$ ").replace(":", "$:")


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, break_long_words=False, break_on_hyphens=False
        ):
            self.output.write("# " + line + "\n")

    def variable(self, key, value, indent=0):
        if value is None:
            return
        if isinstance(value, list):
            value = " ".join(filter(None, value))  # Filter out empty strings.
        self._line("%s = %s" % (key, value), indent)

    def pool(self, name, depth):
        self._line("pool %s" % name)
        self.variable("depth", depth, indent=1)

    def rule(
        self,
        name,
        command,
        description=None,
        depfile=None,
        generator=False,
        pool=None,
        restat=False,
        rspfile=None,
        rspfile_content=None,
        deps=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)
        if generator:
            self.variable("generator", "1", indent=1)
        if pool:
            self.variable("pool", pool, indent=1)
        if restat:
            self.variable("restat", "1", indent=1)
        if rspfile:
            self.variable("rspfile", rspfile, indent=1)
        if rspfile_content:
            self.variable("rspfile_content", rspfile_content, indent=1)
        if deps:
            self.variable("deps", deps, indent=1)

    def build(
        self,
        outputs,
        rule,
        inputs=None,
        implicit=None,
        order_only=None,
        variables=None,
        implicit_outputs=None,
        pool=None,
        dyndep=None,
    ):
        outputs = as_list(outputs)
        out_outputs = [escape_path(x) for x in outputs]
        all_inputs = [escape_path(x) for x in as_list(inputs)]

        if implicit:
            implicit = [escape_path(x) for x in as_list(implicit)]
            all_inputs.append("|")
            all_inputs.extend(implicit)
        if order_only:
            order_only = [escape_path(x) for x in as_list(order_only)]
            all_inputs.append("||")
            all_inputs.extend(order_only)
        if implicit_outputs:
            implicit_outputs = [escape_path(x) for x in as_list(implicit_outputs)]
            out_outputs.append("|")
            out_outputs.extend(implicit_outputs)

        self._line(
            "build %s: %s" % (" ".join(out_outputs), " ".join([rule] + all_inputs))
        )
        if pool is not None:
            self._line("  pool = %s" % pool)
        if dyndep is not None:
            self._line("  dyndep = %s" % dyndep)

        if variables:
            if isinstance(variables, dict):
                iterator = iter(variables.items())
            else:
                iterator = iter(variables)

            for key, val in iterator:
                self.variable(key, val, indent=1)

        return outputs

    def include(self, path):
        self._line("include %s" % path)

    def subninja(self, path):
        self._line("subninja %s" % path)

    def default(self, paths):
        self._line("default %s" % " ".join(as_list(paths)))

    def _count_dollars_before_index(self, s, i):
        """Returns the number of '$' characters right in front of s[i]."""
        dollar_count = 0
        dollar_index = i - 1
        while dollar_index > 0 and s[dollar_index] == "$":
            dollar_count += 1
            dollar_index -= 1
        return dollar_count

    def _line(self, text, indent=0):
        """Write 'text' word-wrapped at self.width characters."""
        leading_space = "  " * indent
        while len(leading_space) + len(text) > self.width:
            # The text is too wide; wrap if possible.

            # Find the rightmost space that would obey our width constraint and
            # that's not an escaped space.
            available_space = self.width - len(leading_space) - len(" $")
            space = available_space
            while True:
                space = text.rfind(" ", 0, space)
                if space < 0 or self._count_dollars_before_index(text, space) % 2 == 0:
                    break

            if space < 0:
                # No such space; just use the first unescaped space we can find.
                space = available_space - 1
                while True:
                    space = text.find(" ", space + 1)
                    if (
                        space < 0
                        or self._count_dollars_before_index(text, space) % 2 == 0
                    ):
                        break
            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 close(self):
        self.output.close()


def as_list(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: '$'.
    return string.replace("$", "$$")


def expand(string, vars, local_vars={}):
    """Expand a string containing $vars as Ninja would.

    Note: doesn't handle the full Ninja variable syntax, but it's enough
    to make configure.py's use of it work.
    """

    def exp(m):
        var = m.group(1)
        if var == "$":
            return "$"
        return local_vars.get(var, vars.get(var, ""))

    return re.sub(r"\$(\$|\w*)", exp, string)