py: implement input

Author: aisk

py/run.go

@@ -105,6 +105,11 @@ var (
 	// Compiles a python buffer into a py.Code object.
 	// Returns a py.Code object or otherwise an error.
 	Compile func(src, srcDesc string, mode CompileMode, flags int, dont_inherit bool) (*Code, error)
+
+	// InputHook is an optional function that can be set to provide a custom input
+	// mechanism for the input() builtin. If nil, input() reads from sys.stdin.
+	// This is used by the REPL to integrate with the liner library.
+	InputHook func(prompt string) (string, error)
 )
 
 // RunFile resolves the given pathname, compiles as needed, executes the code in the given module, and returns the Module to indicate success.

repl/cli/cli.go

@@ -12,6 +12,7 @@ import (
 	"os/user"
 	"path/filepath"
 
+	"github.com/go-python/gpython/py"
 	"github.com/go-python/gpython/repl"
 	"github.com/peterh/liner"
 )
@@ -124,6 +125,13 @@ func RunREPL(replCtx *repl.REPL) error {
 	rl := newReadline(replCtx)
 	replCtx.SetUI(rl)
 	defer rl.Close()
+
+	// Set up InputHook for the input() builtin function
+	py.InputHook = func(prompt string) (string, error) {
+		return rl.Prompt(prompt)
+	}
+	defer func() { py.InputHook = nil }()
+
 	err := rl.ReadHistory()
 	if err != nil {
 		if !os.IsNotExist(err) {

stdlib/builtin/builtin.go

@@ -6,7 +6,9 @@
 package builtin
 
 import (
+	"bufio"
 	"fmt"
+	"io"
 	"math/big"
 	"strconv"
 	"unicode/utf8"
@@ -44,7 +46,7 @@ func init() {
 		// py.MustNewMethod("hash", builtin_hash, 0, hash_doc),
 		py.MustNewMethod("hex", builtin_hex, 0, hex_doc),
 		// py.MustNewMethod("id", builtin_id, 0, id_doc),
-		// py.MustNewMethod("input", builtin_input, 0, input_doc),
+		py.MustNewMethod("input", builtin_input, 0, input_doc),
 		py.MustNewMethod("isinstance", builtin_isinstance, 0, isinstance_doc),
 		// py.MustNewMethod("issubclass", builtin_issubclass, 0, issubclass_doc),
 		py.MustNewMethod("iter", builtin_iter, 0, iter_doc),
@@ -1181,6 +1183,82 @@ func builtin_chr(self py.Object, args py.Tuple) (py.Object, error) {
 	return py.String(buf[:n]), nil
 }
 
+const input_doc = `input([prompt]) -> string
+
+Read a string from standard input.  The trailing newline is stripped.
+The prompt string, if given, is printed to standard output without a
+trailing newline before reading input.
+If the user hits EOF (*nix: Ctrl-D, Windows: Ctrl-Z+Return), raise EOFError.
+On *nix systems, GNU readline is used if enabled.`
+
+func builtin_input(self py.Object, args py.Tuple) (py.Object, error) {
+	var prompt py.Object = py.None
+
+	err := py.UnpackTuple(args, nil, "input", 0, 1, &prompt)
+	if err != nil {
+		return nil, err
+	}
+
+	// Use InputHook if available (e.g., in REPL mode)
+	if py.InputHook != nil {
+		promptStr := ""
+		if prompt != py.None {
+			promptStr = string(prompt.(py.String))
+		}
+		line, err := py.InputHook(promptStr)
+		if err != nil {
+			if err == io.EOF {
+				return nil, py.ExceptionNewf(py.EOFError, "EOF when reading a line")
+			}
+			return nil, err
+		}
+		return py.String(line), nil
+	}
+
+	sysModule, err := self.(*py.Module).Context.GetModule("sys")
+	if err != nil {
+		return nil, err
+	}
+
+	stdin := sysModule.Globals["stdin"]
+	stdout := sysModule.Globals["stdout"]
+
+	if prompt != py.None {
+		write, err := py.GetAttrString(stdout, "write")
+		if err != nil {
+			return nil, err
+		}
+		_, err = py.Call(write, py.Tuple{prompt}, nil)
+		if err != nil {
+			return nil, err
+		}
+
+		flush, err := py.GetAttrString(stdout, "flush")
+		if err == nil {
+			py.Call(flush, nil, nil)
+		}
+	}
+
+	file := stdin.(*py.File)
+	reader := bufio.NewReader(file.File)
+	line, err := reader.ReadString('\n')
+	if err != nil {
+		if err.Error() == "EOF" {
+			return nil, py.ExceptionNewf(py.EOFError, "EOF when reading a line")
+		}
+		return nil, err
+	}
+
+	if len(line) > 0 && line[len(line)-1] == '\n' {
+		line = line[:len(line)-1]
+		if len(line) > 0 && line[len(line)-1] == '\r' {
+			line = line[:len(line)-1]
+		}
+	}
+
+	return py.String(line), nil
+}
+
 const locals_doc = `locals() -> dictionary
 
 Update and return a dictionary containing the current scope's local variables.`