flag.go

Documentation: cmd/go/internal/base

     1  // Copyright 2017 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package base
     6  
     7  import (
     8  	"flag"
     9  	"fmt"
    10  
    11  	"cmd/go/internal/cfg"
    12  	"cmd/go/internal/fsys"
    13  	"cmd/internal/quoted"
    14  )
    15  
    16  // A StringsFlag is a command-line flag that interprets its argument
    17  // as a space-separated list of possibly-quoted strings.
    18  type StringsFlag []string
    19  
    20  func (v *StringsFlag) Set(s string) error {
    21  	var err error
    22  	*v, err = quoted.Split(s)
    23  	if *v == nil {
    24  		*v = []string{}
    25  	}
    26  	return err
    27  }
    28  
    29  func (v *StringsFlag) String() string {
    30  	return "<StringsFlag>"
    31  }
    32  
    33  // explicitStringFlag is like a regular string flag, but it also tracks whether
    34  // the string was set explicitly to a non-empty value.
    35  type explicitStringFlag struct {
    36  	value    *string
    37  	explicit *bool
    38  }
    39  
    40  func (f explicitStringFlag) String() string {
    41  	if f.value == nil {
    42  		return ""
    43  	}
    44  	return *f.value
    45  }
    46  
    47  func (f explicitStringFlag) Set(v string) error {
    48  	*f.value = v
    49  	if v != "" {
    50  		*f.explicit = true
    51  	}
    52  	return nil
    53  }
    54  
    55  // AddBuildFlagsNX adds the -n and -x build flags to the flag set.
    56  func AddBuildFlagsNX(flags *flag.FlagSet) {
    57  	flags.BoolVar(&cfg.BuildN, "n", false, "")
    58  	flags.BoolVar(&cfg.BuildX, "x", false, "")
    59  }
    60  
    61  // AddChdirFlag adds the -C flag to the flag set.
    62  func AddChdirFlag(flags *flag.FlagSet) {
    63  	// The usage message is never printed, but it's used in chdir_test.go
    64  	// to identify that the -C flag is from AddChdirFlag.
    65  	flags.Func("C", "AddChdirFlag", ChdirFlag)
    66  }
    67  
    68  // AddModFlag adds the -mod build flag to the flag set.
    69  func AddModFlag(flags *flag.FlagSet) {
    70  	flags.Var(explicitStringFlag{value: &cfg.BuildMod, explicit: &cfg.BuildModExplicit}, "mod", "")
    71  }
    72  
    73  // AddModCommonFlags adds the module-related flags common to build commands
    74  // and 'go mod' subcommands.
    75  func AddModCommonFlags(flags *flag.FlagSet) {
    76  	flags.BoolVar(&cfg.ModCacheRW, "modcacherw", false, "")
    77  	flags.StringVar(&cfg.ModFile, "modfile", "", "")
    78  	flags.StringVar(&fsys.OverlayFile, "overlay", "", "")
    79  }
    80  
    81  func ChdirFlag(s string) error {
    82  	// main handles -C by removing it from the command line.
    83  	// If we see one during flag parsing, that's an error.
    84  	return fmt.Errorf("-C flag must be first flag on command line")
    85  }
    86
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