urfave-cli/generate-flag-types
Michael Schuett ff1c0b58dd Start of category flag support
This adds what I think needs to be done to support categories for flags
but we will see if that works. It also forces the scripts to use python2
since they blow up under python3 which is becoming the default python on
many linux systems.

Small fix to app_test as well so it conforms to the new Flag interface.
2019-01-27 01:41:06 -05:00

263 lines
8.2 KiB
Python
Executable File

#!/usr/bin/env python2
"""
The flag types that ship with the cli library have many things in common, and
so we can take advantage of the `go generate` command to create much of the
source code from a list of definitions. These definitions attempt to cover
the parts that vary between flag types, and should evolve as needed.
An example of the minimum definition needed is:
{
"name": "SomeType",
"type": "sometype",
"context_default": "nil"
}
In this example, the code generated for the `cli` package will include a type
named `SomeTypeFlag` that is expected to wrap a value of type `sometype`.
Fetching values by name via `*cli.Context` will default to a value of `nil`.
A more complete, albeit somewhat redundant, example showing all available
definition keys is:
{
"name": "VeryMuchType",
"type": "*VeryMuchType",
"value": true,
"dest": false,
"doctail": " which really only wraps a []float64, oh well!",
"context_type": "[]float64",
"context_default": "nil",
"parser": "parseVeryMuchType(f.Value.String())",
"parser_cast": "[]float64(parsed)"
}
The meaning of each field is as follows:
name (string) - The type "name", which will be suffixed with
`Flag` when generating the type definition
for `cli` and the wrapper type for `altsrc`
type (string) - The type that the generated `Flag` type for `cli`
is expected to "contain" as its `.Value` member
value (bool) - Should the generated `cli` type have a `Value`
member?
dest (bool) - Should the generated `cli` type support a
destination pointer?
doctail (string) - Additional docs for the `cli` flag type comment
context_type (string) - The literal type used in the `*cli.Context`
reader func signature
context_default (string) - The literal value used as the default by the
`*cli.Context` reader funcs when no value is
present
parser (string) - Literal code used to parse the flag `f`,
expected to have a return signature of
(value, error)
parser_cast (string) - Literal code used to cast the `parsed` value
returned from the `parser` code
"""
from __future__ import print_function, unicode_literals
import argparse
import json
import os
import subprocess
import sys
import tempfile
import textwrap
class _FancyFormatter(argparse.ArgumentDefaultsHelpFormatter,
argparse.RawDescriptionHelpFormatter):
pass
def main(sysargs=sys.argv[:]):
parser = argparse.ArgumentParser(
description='Generate flag type code!',
formatter_class=_FancyFormatter)
parser.add_argument(
'package',
type=str, default='cli', choices=_WRITEFUNCS.keys(),
help='Package for which flag types will be generated'
)
parser.add_argument(
'-i', '--in-json',
type=argparse.FileType('r'),
default=sys.stdin,
help='Input JSON file which defines each type to be generated'
)
parser.add_argument(
'-o', '--out-go',
type=argparse.FileType('w'),
default=sys.stdout,
help='Output file/stream to which generated source will be written'
)
parser.epilog = __doc__
args = parser.parse_args(sysargs[1:])
_generate_flag_types(_WRITEFUNCS[args.package], args.out_go, args.in_json)
return 0
def _generate_flag_types(writefunc, output_go, input_json):
types = json.load(input_json)
tmp = tempfile.NamedTemporaryFile(suffix='.go', delete=False)
writefunc(tmp, types)
tmp.close()
new_content = subprocess.check_output(
['goimports', tmp.name]
).decode('utf-8')
print(new_content, file=output_go, end='')
output_go.flush()
os.remove(tmp.name)
def _set_typedef_defaults(typedef):
typedef.setdefault('doctail', '')
typedef.setdefault('context_type', typedef['type'])
typedef.setdefault('dest', True)
typedef.setdefault('value', True)
typedef.setdefault('parser', 'f.Value, error(nil)')
typedef.setdefault('parser_cast', 'parsed')
def _write_cli_flag_types(outfile, types):
_fwrite(outfile, """\
package cli
// WARNING: This file is generated!
""")
for typedef in types:
_set_typedef_defaults(typedef)
_fwrite(outfile, """\
// {name}Flag is a flag with type {type}{doctail}
type {name}Flag struct {{
Name string
Usage string
EnvVar string
FilePath string
Hidden bool
Category string
""".format(**typedef))
if typedef['value']:
_fwrite(outfile, """\
Value {type}
""".format(**typedef))
if typedef['dest']:
_fwrite(outfile, """\
Destination *{type}
""".format(**typedef))
_fwrite(outfile, "\n}\n\n")
_fwrite(outfile, """\
// String returns a readable representation of this value
// (for usage defaults)
func (f {name}Flag) String() string {{
return FlagStringer(f)
}}
// GetName returns the name of the flag
func (f {name}Flag) GetName() string {{
return f.Name
}}
// GetHidden lets us know if the flag is hidden or not
func (f {name}Flag) GetHidden() bool {{
return f.Hidden
}}
// {name} looks up the value of a local {name}Flag, returns
// {context_default} if not found
func (c *Context) {name}(name string) {context_type} {{
return lookup{name}(name, c.flagSet)
}}
// Global{name} looks up the value of a global {name}Flag, returns
// {context_default} if not found
func (c *Context) Global{name}(name string) {context_type} {{
if fs := lookupGlobalFlagSet(name, c); fs != nil {{
return lookup{name}(name, fs)
}}
return {context_default}
}}
func lookup{name}(name string, set *flag.FlagSet) {context_type} {{
f := set.Lookup(name)
if f != nil {{
parsed, err := {parser}
if err != nil {{
return {context_default}
}}
return {parser_cast}
}}
return {context_default}
}}
""".format(**typedef))
def _write_altsrc_flag_types(outfile, types):
_fwrite(outfile, """\
package altsrc
import (
"gopkg.in/urfave/cli.v1"
)
// WARNING: This file is generated!
""")
for typedef in types:
_set_typedef_defaults(typedef)
_fwrite(outfile, """\
// {name}Flag is the flag type that wraps cli.{name}Flag to allow
// for other values to be specified
type {name}Flag struct {{
cli.{name}Flag
set *flag.FlagSet
}}
// New{name}Flag creates a new {name}Flag
func New{name}Flag(fl cli.{name}Flag) *{name}Flag {{
return &{name}Flag{{{name}Flag: fl, set: nil}}
}}
// Apply saves the flagSet for later usage calls, then calls the
// wrapped {name}Flag.Apply
func (f *{name}Flag) Apply(set *flag.FlagSet) {{
f.set = set
f.{name}Flag.Apply(set)
}}
// ApplyWithError saves the flagSet for later usage calls, then calls the
// wrapped {name}Flag.ApplyWithError
func (f *{name}Flag) ApplyWithError(set *flag.FlagSet) error {{
f.set = set
return f.{name}Flag.ApplyWithError(set)
}}
""".format(**typedef))
def _fwrite(outfile, text):
print(textwrap.dedent(text), end='', file=outfile)
_WRITEFUNCS = {
'cli': _write_cli_flag_types,
'altsrc': _write_altsrc_flag_types
}
if __name__ == '__main__':
sys.exit(main())