runes.Reader: WIP

Signed-off-by: Alejandro Mery <amery@jpi.io>

lexer/error.go

@@ -1,45 +0,0 @@
-package lexer
-
-import (
-	"fmt"
-	"strings"
-)
-
-var (
-	_ error = (*Error)(nil)
-)
-
-// Error represents a generic parsing error
-type Error struct {
-	Filename string
-	Line     int
-	Column   int
-
-	Content string
-	Err     error
-}
-
-func (err Error) Error() string {
-	var s []string
-
-	switch {
-	case err.Line > 0 || err.Column > 0:
-		s = append(s, fmt.Sprintf("%s:%v:%v", err.Filename, err.Line, err.Column))
-	case err.Filename != "":
-		s = append(s, err.Filename)
-	}
-
-	if err.Err != nil {
-		s = append(s, err.Err.Error())
-	}
-
-	if err.Content != "" {
-		s = append(s, fmt.Sprintf("%q", err.Content))
-	}
-
-	return strings.Join(s, ": ")
-}
-
-func (err Error) Unwrap() error {
-	return err.Err
-}

lexer/lexer.go

@@ -1,2 +0,0 @@
-// Package lexer provides basic helpers to implement parsers
-package lexer

lexer/position.go

@@ -1,66 +0,0 @@
-package lexer
-
-import "fmt"
-
-// Position indicates a line and column pair on a file.
-// Counting starts at 1.
-type Position struct {
-	Line   int
-	Column int
-}
-
-// String generates a pretty "(Line, Column)"" representation of the Position
-func (p Position) String() string {
-	if p.Line == 0 {
-		p.Reset()
-	}
-
-	return fmt.Sprintf("(%v, %v)", p.Line, p.Column)
-}
-
-// GoString generates a string representation of the Position for %#v usage
-func (p Position) GoString() string {
-	if p.Line == 0 {
-		p.Reset()
-	}
-
-	return fmt.Sprintf("lexer.Position{%v, %v}", p.Line, p.Column)
-}
-
-// Reset places a position at (1,1)
-func (p *Position) Reset() {
-	p.Line, p.Column = 1, 1
-}
-
-// Step moves the column one place
-func (p *Position) Step() {
-	if p.Line == 0 {
-		p.Reset()
-	}
-
-	p.Column++
-}
-
-// StepN moves the column N places forward
-func (p *Position) StepN(n int) {
-	if p.Line == 0 {
-		p.Reset()
-	}
-
-	switch {
-	case n > 0:
-		p.Column += n
-	default:
-		panic(fmt.Errorf("invalid %v increment", n))
-	}
-}
-
-// StepLine moves position to the start of the next line
-func (p *Position) StepLine() {
-	if p.Line == 0 {
-		p.Reset()
-	}
-
-	p.Line++
-	p.Column = 1
-}

readcloser.go

@@ -7,6 +7,11 @@ import (
 	"strings"
 )
 
+var (
+	_ io.Reader = (*ReadCloser)(nil)
+	_ io.Closer = (*ReadCloser)(nil)
+)
+
 // ReadCloser adds a Close() to Readers without one
 type ReadCloser struct {
 	r io.Reader
@@ -27,38 +32,37 @@ func (rc *ReadCloser) Read(b []byte) (int, error) {
 // remove it if it doesn't support Close() and fail
 // if closed twice
 func (rc *ReadCloser) Close() error {
-	switch {
+	switch p := rc.r.(type) {
-	case rc.r != nil:
+	case io.Closer:
+		return p.Close()
+	case nil:
+		return fs.ErrClosed
+	default:
 		rc.r = nil
 		return nil
-	default:
-		return fs.ErrClosed
 	}
 }
 
 // NewReadCloser wraps a [io.Reader] to satisfy
-// [io.ReadCloser] if needed
+// [io.ReadCloser]
-func NewReadCloser(r io.Reader) io.ReadCloser {
+func NewReadCloser(r io.Reader) *ReadCloser {
-	switch p := r.(type) {
+	if r == nil {
-	case io.ReadCloser:
-		return p
-	case nil:
 		return nil
-	default:
+	}
+
 	return &ReadCloser{
 		r: r,
 	}
-	}
 }
 
 // NewReadCloserBytes wraps a bytes slice to implement
 // a [io.ReadCloser]
-func NewReadCloserBytes(b []byte) io.ReadCloser {
+func NewReadCloserBytes(b []byte) *ReadCloser {
 	return NewReadCloser(bytes.NewReader(b))
 }
 
 // NewReadCloserString wraps a string to implement
 // a [io.ReadCloser]
-func NewReadCloserString(s string) io.ReadCloser {
+func NewReadCloserString(s string) *ReadCloser {
 	return NewReadCloser(strings.NewReader(s))
 }

runes/docs.go

@@ -0,0 +1,2 @@
+// Package runes helps us work with runes
+package runes

runes/reader.go

@@ -1,8 +1,7 @@
-package lexer
+package runes
 
 import (
 	"bytes"
-	"errors"
 	"io"
 	"strings"
 	"unicode/utf8"
@@ -23,12 +22,6 @@ var (
 	_ io.RuneScanner = (*Reader)(nil)
 )
 
-var (
-	// ErrInvalidUnreadRune indicates UnreadRune() was calls after an
-	// action other than a successful ReadRune()
-	ErrInvalidUnreadRune = errors.New("invalid UnreadRune() call")
-)
-
 // Reader is a RuneReader aimed at implementing text parsers
 type Reader struct {
 	src io.Reader
@@ -36,8 +29,6 @@ type Reader struct {
 	buf    []byte
 	off    int
 	cursor int
-
-	lastRuneSize int
 }
 
 // String returns what's already Read but not yet emitted or discarded
@@ -64,9 +55,6 @@ func (b *Reader) Discard() {
 		// step
 		b.off = b.cursor
 	}
-
-	// and prevent UnreadRune()
-	b.lastRuneSize = -1
 }
 
 // ready tells how many bytes are ready to decode
@@ -152,8 +140,6 @@ func (b *Reader) ReadRune() (rune, int, error) {
 	for {
 		err := b.needsBytes(count)
 		if err != nil {
-			b.lastRuneSize = -1
-
 			return 0, 0, err
 		}
 
@@ -168,23 +154,12 @@ func (b *Reader) ReadRune() (rune, int, error) {
 
 	// decode rune
 	r, l := utf8.DecodeRune(b.buf[b.cursor:])
-	// step over
-	b.cursor += l
-	// and remember for UnreadRune()
-	b.lastRuneSize = l
-
 	return r, l, nil
 }
 
 // UnreadRune moves the cursor where it was before the last call to ReadRune
-func (b *Reader) UnreadRune() error {
+func (*Reader) UnreadRune() error {
-	if b.lastRuneSize > 0 {
-		b.cursor -= b.lastRuneSize
-		b.lastRuneSize = -1
 	return nil
-	}
-
-	return ErrInvalidUnreadRune
 }
 
 // PeekRune returns information about the next rune without moving the