func-*.go modules renamed as builtin-*.go.

Also changed and exported some identiefier relatet to the builtin feature

builtin-os-file.go

@@ -0,0 +1,214 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// builtin-os-file.go
+package expr
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+)
+
+type osHandle interface {
+	getFile() *os.File
+}
+
+type osWriter struct {
+	fh     *os.File
+	writer *bufio.Writer
+}
+
+func (h *osWriter) TypeName() string {
+	return "osWriter"
+}
+
+func (h *osWriter) String() string {
+	return "writer"
+}
+
+func (h *osWriter) getFile() *os.File {
+	return h.fh
+}
+
+type osReader struct {
+	fh     *os.File
+	reader *bufio.Reader
+}
+
+func (h *osReader) TypeName() string {
+	return "osReader"
+}
+
+func (h *osReader) String() string {
+	return "reader"
+}
+
+func (h *osReader) getFile() *os.File {
+	return h.fh
+}
+
+func errMissingFilePath(funcName string) error {
+	return fmt.Errorf("%s(): missing or invalid file path", funcName)
+}
+
+func errInvalidFileHandle(funcName string, v any) error {
+	if v != nil {
+		return fmt.Errorf("%s(): invalid file handle %v [%T]", funcName, v, v)
+	} else {
+		return fmt.Errorf("%s(): invalid file handle", funcName)
+	}
+}
+
+func createFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	if filePath, ok := args[0].(string); ok && len(filePath) > 0 {
+		var fh *os.File
+		if fh, err = os.Create(filePath); err == nil {
+			result = &osWriter{fh: fh, writer: bufio.NewWriter(fh)}
+		}
+	} else {
+		err = errMissingFilePath("createFile")
+	}
+	return
+}
+
+func openFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	if filePath, ok := args[0].(string); ok && len(filePath) > 0 {
+		var fh *os.File
+		if fh, err = os.Open(filePath); err == nil {
+			result = &osReader{fh: fh, reader: bufio.NewReader(fh)}
+		}
+	} else {
+		err = errMissingFilePath("openFile")
+	}
+	return
+}
+
+func appendFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	if filePath, ok := args[0].(string); ok && len(filePath) > 0 {
+		var fh *os.File
+		if fh, err = os.OpenFile(filePath, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0660); err == nil {
+			result = &osWriter{fh: fh, writer: bufio.NewWriter(fh)}
+		}
+	} else {
+		err = errMissingFilePath("openFile")
+	}
+	return
+}
+
+func closeFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
+
+	if handle, ok = args[0].(osHandle); !ok {
+		invalidFileHandle = args[0]
+	}
+
+	if handle != nil {
+		if fh := handle.getFile(); fh != nil {
+			if w, ok := handle.(*osWriter); ok {
+				err = w.writer.Flush()
+			}
+
+			if err == nil {
+				err = fh.Close()
+			}
+		}
+	}
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("closeFileFunc", handle)
+	}
+	result = err == nil
+	return
+}
+
+func writeFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
+
+	if handle, ok = args[0].(osHandle); !ok {
+		invalidFileHandle = args[0]
+	}
+
+	if handle != nil {
+		if w, ok := handle.(*osWriter); ok {
+			result, err = fmt.Fprint(w.writer, args[1:]...)
+		} else {
+			invalidFileHandle = handle
+		}
+	}
+
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("writeFileFunc", invalidFileHandle)
+	}
+	return
+}
+
+func readFileFunc(ctx ExprContext, name string, args []any) (result any, err error) {
+	var handle osHandle
+	var invalidFileHandle any
+	var ok bool
+
+	result = nil
+	if handle, ok = args[0].(osHandle); !ok || args[0] == nil {
+		invalidFileHandle = args[0]
+	}
+
+	if handle != nil {
+		if r, ok := handle.(*osReader); ok {
+			var limit byte = '\n'
+			var v string
+			if s, ok := args[1].(string); ok && len(s) > 0 {
+				limit = s[0]
+			}
+
+			if v, err = r.reader.ReadString(limit); err == nil {
+				if len(v) > 0 && v[len(v)-1] == limit {
+					result = v[0 : len(v)-1]
+				} else {
+					result = v
+				}
+			}
+			if err == io.EOF {
+				err = nil
+			}
+		} else {
+			invalidFileHandle = handle
+		}
+	}
+
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle("readFileFunc", invalidFileHandle)
+	}
+	return
+}
+
+func ImportOsFuncs(ctx ExprContext) {
+	ctx.RegisterFunc("openFile", NewGolangFunctor(openFileFunc), TypeHandle, []ExprFuncParam{
+		NewFuncParam(ParamFilepath),
+	})
+	ctx.RegisterFunc("appendFile", NewGolangFunctor(appendFileFunc), TypeHandle, []ExprFuncParam{
+		NewFuncParam(ParamFilepath),
+	})
+	ctx.RegisterFunc("createFile", NewGolangFunctor(createFileFunc), TypeHandle, []ExprFuncParam{
+		NewFuncParam(ParamFilepath),
+	})
+	ctx.RegisterFunc("writeFile", NewGolangFunctor(writeFileFunc), TypeInt, []ExprFuncParam{
+		NewFuncParam(TypeHandle),
+		NewFuncParamFlagDef(TypeItem, PfDefault|PfRepeat, ""),
+	})
+	ctx.RegisterFunc("readFile", NewGolangFunctor(readFileFunc), TypeString, []ExprFuncParam{
+		NewFuncParam(TypeHandle),
+		NewFuncParamFlagDef("limitCh", PfDefault, "\n"),
+	})
+	ctx.RegisterFunc("closeFile", NewGolangFunctor(closeFileFunc), TypeBoolean, []ExprFuncParam{
+		NewFuncParam(TypeHandle),
+	})
+}
+
+func init() {
+	RegisterBuiltinModule("os.file", ImportOsFuncs, "Operating system file functions")
+}