Merge pull request #1836 from dearchap/issue_1720

Fix:(issue_1720) Add support for reading args from stdin

command.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"bufio"
 	"context"
 	"flag"
 	"fmt"
@@ -10,6 +11,7 @@ import (
 	"reflect"
 	"sort"
 	"strings"
+	"unicode"
 )
 
 const (
@@ -125,6 +127,9 @@ type Command struct {
 	MutuallyExclusiveFlags []MutuallyExclusiveFlags
 	// Arguments to parse for this command
 	Arguments []Argument
+	// Whether to read arguments from stdin
+	// applicable to root command only
+	ReadArgsFromStdin bool
 
 	// categories contains the categorized commands and is populated on app startup
 	categories CommandCategories
@@ -340,6 +345,83 @@ func (cmd *Command) ensureHelp() {
 	}
 }
 
+func (cmd *Command) parseArgsFromStdin() ([]string, error) {
+	type state int
+	const (
+		STATE_SEARCH_FOR_TOKEN state = -1
+		STATE_IN_STRING        state = 0
+	)
+
+	st := STATE_SEARCH_FOR_TOKEN
+	linenum := 1
+	token := ""
+	args := []string{}
+
+	breader := bufio.NewReader(cmd.Reader)
+
+outer:
+	for {
+		ch, _, err := breader.ReadRune()
+		if err == io.EOF {
+			switch st {
+			case STATE_SEARCH_FOR_TOKEN:
+				if token != "--" {
+					args = append(args, token)
+				}
+			case STATE_IN_STRING:
+				// make sure string is not empty
+				for _, t := range token {
+					if !unicode.IsSpace(t) {
+						args = append(args, token)
+					}
+				}
+			}
+			break outer
+		}
+		if err != nil {
+			return nil, err
+		}
+		switch st {
+		case STATE_SEARCH_FOR_TOKEN:
+			if unicode.IsSpace(ch) || ch == '"' {
+				if ch == '\n' {
+					linenum++
+				}
+				if token != "" {
+					// end the processing here
+					if token == "--" {
+						break outer
+					}
+					args = append(args, token)
+					token = ""
+				}
+				if ch == '"' {
+					st = STATE_IN_STRING
+				}
+				continue
+			}
+			token += string(ch)
+		case STATE_IN_STRING:
+			if ch != '"' {
+				token += string(ch)
+			} else {
+				if token != "" {
+					args = append(args, token)
+					token = ""
+				}
+				/*else {
+					//TODO. Should we pass in empty strings ?
+				}*/
+				st = STATE_SEARCH_FOR_TOKEN
+			}
+		}
+	}
+
+	tracef("parsed stdin args as %v (cmd=%[2]q)", args, cmd.Name)
+
+	return args, nil
+}
+
 // Run is the entry point to the command graph. The positional
 // arguments are parsed according to the Flag and Command
 // definitions and the matching Action functions are run.
@@ -353,6 +435,13 @@ func (cmd *Command) Run(ctx context.Context, osArgs []string) (deferErr error) {
 	}
 
 	if cmd.parent == nil {
+		if cmd.ReadArgsFromStdin {
+			if args, err := cmd.parseArgsFromStdin(); err != nil {
+				return err
+			} else {
+				osArgs = append(osArgs, args...)
+			}
+		}
 		// handle the completion flag separately from the flagset since
 		// completion could be attempted after a flag, but before its value was put
 		// on the command line. this causes the flagset to interpret the completion

command_test.go

@@ -3862,3 +3862,168 @@ func TestCommand_ParentCommand_Set(t *testing.T) {
 		t.Errorf("expect nil. set parent context flag return err: %s", err)
 	}
 }
+
+func TestCommandReadArgsFromStdIn(t *testing.T) {
+
+	tests := []struct {
+		name          string
+		input         string
+		args          []string
+		expectedInt   int64
+		expectedFloat float64
+		expectedSlice []string
+		expectError   bool
+	}{
+		{
+			name:          "empty",
+			input:         "",
+			args:          []string{"foo"},
+			expectedInt:   0,
+			expectedFloat: 0.0,
+			expectedSlice: []string{},
+		},
+		{
+			name: "empty2",
+			input: `
+			
+			`,
+			args:          []string{"foo"},
+			expectedInt:   0,
+			expectedFloat: 0.0,
+			expectedSlice: []string{},
+		},
+		{
+			name:          "intflag-from-input",
+			input:         "--if=100",
+			args:          []string{"foo"},
+			expectedInt:   100,
+			expectedFloat: 0.0,
+			expectedSlice: []string{},
+		},
+		{
+			name: "intflag-from-input2",
+			input: `
+			--if 
+
+			100`,
+			args:          []string{"foo"},
+			expectedInt:   100,
+			expectedFloat: 0.0,
+			expectedSlice: []string{},
+		},
+		{
+			name: "multiflag-from-input",
+			input: `
+			--if
+
+			100
+			--ff      100.1
+
+			--ssf hello
+			--ssf
+
+			"hello	
+  123
+44"
+			`,
+			args:          []string{"foo"},
+			expectedInt:   100,
+			expectedFloat: 100.1,
+			expectedSlice: []string{"hello", "hello\t\n  123\n44"},
+		},
+		{
+			name: "end-args",
+			input: `
+			--if
+
+			100
+			--
+			--ff      100.1
+
+			--ssf hello
+			--ssf
+
+			hell02
+			`,
+			args:          []string{"foo"},
+			expectedInt:   100,
+			expectedFloat: 0,
+			expectedSlice: []string{},
+		},
+		{
+			name: "invalid string",
+			input: `
+			"
+			`,
+			args:          []string{"foo"},
+			expectedInt:   0,
+			expectedFloat: 0,
+			expectedSlice: []string{},
+		},
+		{
+			name: "invalid string2",
+			input: `
+			--if
+			"
+			`,
+			args:        []string{"foo"},
+			expectError: true,
+		},
+		{
+			name: "incomplete string",
+			input: `
+			--ssf
+			"
+			hello
+			`,
+			args:          []string{"foo"},
+			expectedSlice: []string{"hello"},
+		},
+	}
+
+	for _, tst := range tests {
+		t.Run(tst.name, func(t *testing.T) {
+			r := require.New(t)
+
+			fp, err := os.CreateTemp("", "readargs")
+			r.NoError(err)
+			_, err = fp.Write([]byte(tst.input))
+			r.NoError(err)
+			fp.Close()
+
+			cmd := buildMinimalTestCommand()
+			cmd.ReadArgsFromStdin = true
+			cmd.Reader, err = os.Open(fp.Name())
+			r.NoError(err)
+			cmd.Flags = []Flag{
+				&IntFlag{
+					Name: "if",
+				},
+				&FloatFlag{
+					Name: "ff",
+				},
+				&StringSliceFlag{
+					Name: "ssf",
+				},
+			}
+
+			actionCalled := false
+			cmd.Action = func(ctx context.Context, c *Command) error {
+				r.Equal(tst.expectedInt, c.Int("if"))
+				r.Equal(tst.expectedFloat, c.Float("ff"))
+				r.Equal(tst.expectedSlice, c.StringSlice("ssf"))
+				actionCalled = true
+				return nil
+			}
+
+			err = cmd.Run(context.Background(), tst.args)
+			if !tst.expectError {
+				r.NoError(err)
+				r.True(actionCalled)
+			} else {
+				r.Error(err)
+			}
+
+		})
+	}
+}

godoc-current.txt

@@ -394,6 +394,9 @@ type Command struct {
 	MutuallyExclusiveFlags []MutuallyExclusiveFlags
 	// Arguments to parse for this command
 	Arguments []Argument
+	// Whether to read arguments from stdin
+	// applicable to root command only
+	ReadArgsFromStdin bool
 
 	// Has unexported fields.
 }

testdata/godoc-v3.x.txt

@@ -394,6 +394,9 @@ type Command struct {
 	MutuallyExclusiveFlags []MutuallyExclusiveFlags
 	// Arguments to parse for this command
 	Arguments []Argument
+	// Whether to read arguments from stdin
+	// applicable to root command only
+	ReadArgsFromStdin bool
 
 	// Has unexported fields.
 }