py,repl/cli,stdlib/builtin: implement input

- py: implement input
- add missing getline method on py.File
- add parameters to readfile and add test

Author: aisk

py/file.go

@@ -31,6 +31,9 @@ func init() {
 	FileType.Dict["flush"] = MustNewMethod("flush", func(self Object) (Object, error) {
 		return self.(*File).Flush()
 	}, 0, "flush() -> Flush the write buffers of the stream if applicable. This does nothing for read-only and non-blocking streams.")
+	FileType.Dict["readline"] = MustNewMethod("readline", func(self Object, args Tuple, kwargs StringDict) (Object, error) {
+		return self.(*File).ReadLine(args, kwargs)
+	}, 0, "readline(size=-1, /) -> Read and return one line from the stream. If size is specified, at most size bytes will be read.\n\nThe line terminator is always b'\\n' for binary files; for text files, the newline argument to open can be used to select the line terminator(s) recognized.")
 }
 
 type FileMode int
@@ -143,6 +146,44 @@ func (o *File) Read(args Tuple, kwargs StringDict) (Object, error) {
 	return o.readResult(b)
 }
 
+func (o *File) ReadLine(args Tuple, kwargs StringDict) (Object, error) {
+	var size Object = None
+	err := UnpackTuple(args, kwargs, "readline", 0, 1, &size)
+	if err != nil {
+		return nil, err
+	}
+	limit := int64(-1)
+	if size != None {
+		pyN, ok := size.(Int)
+		if !ok {
+			return nil, ExceptionNewf(TypeError, "integer argument expected, got '%s'", size.Type().Name)
+		}
+		limit, _ = pyN.GoInt64()
+	}
+
+	var buf []byte
+	b := make([]byte, 1)
+	for {
+		if limit >= 0 && int64(len(buf)) >= limit {
+			break
+		}
+		n, err := o.File.Read(b)
+		if n > 0 {
+			buf = append(buf, b[0])
+			if b[0] == '\n' {
+				break
+			}
+		}
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+	}
+	return o.readResult(buf)
+}
+
 func (o *File) Close() (Object, error) {
 	_ = o.File.Close()
 	return None, nil

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.

py/tests/file.py

@@ -25,6 +25,12 @@
 b = f.read()
 assert b == ''
 
+doc = "readline"
+f2 = open(__file__)
+line = f2.readline()
+assert line == '# Copyright 2018 The go-python Authors.  All rights reserved.\n'
+f2.close()
+
 doc = "write"
 assertRaises(TypeError, f.write, 42)
 

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

@@ -6,9 +6,12 @@
 package builtin
 
 import (
+	"errors"
 	"fmt"
+	"io"
 	"math/big"
 	"strconv"
+	"strings"
 	"unicode/utf8"
 
 	"github.com/go-python/gpython/compile"
@@ -44,7 +47,7 @@ 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 +1184,84 @@ 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.`
+
+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 {
+			s, ok := prompt.(py.String)
+			if !ok {
+				return nil, py.ExceptionNewf(py.TypeError, "input() prompt must be a string")
+			}
+			promptStr = string(s)
+		}
+		line, err := py.InputHook(promptStr)
+		if err != nil {
+			if errors.Is(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)
+		}
+	}
+
+	readline, err := py.GetAttrString(stdin, "readline")
+	if err != nil {
+		return nil, err
+	}
+	result, err := py.Call(readline, nil, nil)
+	if err != nil {
+		return nil, err
+	}
+	line, ok := result.(py.String)
+	if !ok {
+		return nil, py.ExceptionNewf(py.TypeError, "object.readline() should return a str object, got %s", result.Type().Name)
+	}
+	if line == "" {
+		return nil, py.ExceptionNewf(py.EOFError, "EOF when reading a line")
+	}
+	line = py.String(strings.TrimRight(string(line), "\r\n"))
+	return line, nil
+}
+
 const locals_doc = `locals() -> dictionary
 
 Update and return a dictionary containing the current scope's local variables.`

stdlib/builtin/tests/builtin.py

@@ -502,4 +502,16 @@ class C: pass
 assert lib.libvar == 43
 assert lib.libclass().method() == 44
 
+doc="input"
+import sys
+class MockStdin:
+    def __init__(self, line):
+        self._line = line
+    def readline(self):
+        return self._line
+old_stdin = sys.stdin
+sys.stdin = MockStdin("hello\n")
+assert input() == "hello"
+sys.stdin = old_stdin
+
 doc="finished"