Move parser code

parser.go

@@ -1 +1,615 @@
 package toml
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+)
+
+type builder interface {
+	SimpleKey(v []byte)
+
+	StandardTableBegin()
+	StandardTableEnd()
+	ArrayTableBegin()
+	ArrayTableEnd()
+	KeyValBegin()
+	KeyValEnd()
+	ArrayBegin()
+	ArrayEnd()
+	Assignation()
+
+	StringValue(v []byte)
+	BoolValue(b bool)
+}
+
+type parser struct {
+	builder builder
+}
+
+func (p parser) parse(b []byte) error {
+	b, err := p.parseExpression(b)
+	if err != nil {
+		return err
+	}
+	for len(b) > 0 {
+		b, err = p.parseNewline(b)
+		if err != nil {
+			return err
+		}
+
+		b, err = p.parseExpression(b)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p parser) parseNewline(b []byte) ([]byte, error) {
+	if b[0] == '\n' {
+		return b[1:], nil
+	}
+	if b[0] == '\r' {
+		_, rest, err := scanWindowsNewline(b)
+		return rest, err
+	}
+	return nil, fmt.Errorf("expected newline but got %#U", b[0])
+}
+
+func (p parser) parseExpression(b []byte) ([]byte, error) {
+	//expression =  ws [ comment ]
+	//expression =/ ws keyval ws [ comment ]
+	//expression =/ ws table ws [ comment ]
+
+	b = p.parseWhitespace(b)
+
+	if len(b) == 0 {
+		return b, nil
+	}
+
+	if b[0] == '#' {
+		_, rest, err := scanComment(b)
+		return rest, err
+	}
+	if b[0] == '\n' || b[0] == '\r' {
+		return b, nil
+	}
+
+	var err error
+	if b[0] == '[' {
+		b, err = p.parseTable(b)
+	} else {
+		b, err = p.parseKeyval(b)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	b = p.parseWhitespace(b)
+
+	if len(b) > 0 && b[0] == '#' {
+		_, rest, err := scanComment(b)
+		return rest, err
+	}
+
+	return b, nil
+}
+
+func (p parser) parseTable(b []byte) ([]byte, error) {
+	//table = std-table / array-table
+	if len(b) > 1 && b[1] == '[' {
+		return p.parseArrayTable(b)
+	}
+	return p.parseStdTable(b)
+}
+
+func (p parser) parseArrayTable(b []byte) ([]byte, error) {
+	//array-table = array-table-open key array-table-close
+	//array-table-open  = %x5B.5B ws  ; [[ Double left square bracket
+	//array-table-close = ws %x5D.5D  ; ]] Double right square bracket
+
+	p.builder.ArrayTableBegin()
+	defer p.builder.ArrayTableEnd()
+
+	b = b[2:]
+	b = p.parseWhitespace(b)
+	b, err := p.parseKey(b)
+	if err != nil {
+		return nil, err
+	}
+	b = p.parseWhitespace(b)
+	b, err = expect(']', b)
+	if err != nil {
+		return nil, err
+	}
+	return expect(']', b)
+}
+
+func (p parser) parseStdTable(b []byte) ([]byte, error) {
+	//std-table = std-table-open key std-table-close
+	//std-table-open  = %x5B ws     ; [ Left square bracket
+	//std-table-close = ws %x5D     ; ] Right square bracket
+
+	p.builder.StandardTableBegin()
+	defer p.builder.StandardTableEnd()
+
+	b = b[1:]
+	b = p.parseWhitespace(b)
+	b, err := p.parseKey(b)
+	if err != nil {
+		return nil, err
+	}
+	b = p.parseWhitespace(b)
+
+	return expect(']', b)
+}
+
+func (p parser) parseKeyval(b []byte) ([]byte, error) {
+	//keyval = key keyval-sep val
+
+	p.builder.KeyValBegin()
+	defer p.builder.KeyValEnd()
+
+	b, err := p.parseKey(b)
+	if err != nil {
+		return nil, err
+	}
+
+	//keyval-sep = ws %x3D ws ; =
+
+	b = p.parseWhitespace(b)
+	b, err = expect('=', b)
+	if err != nil {
+		return nil, err
+	}
+	p.builder.Assignation()
+	b = p.parseWhitespace(b)
+
+	return p.parseVal(b)
+}
+
+func (p parser) parseVal(b []byte) ([]byte, error) {
+	// val = string / boolean / array / inline-table / date-time / float / integer
+	if len(b) == 0 {
+		return nil, fmt.Errorf("expected value, not eof")
+	}
+
+	var err error
+	c := b[0]
+
+	switch c {
+	// strings
+	case '"':
+		var v []byte
+		if scanFollowsMultilineBasicStringDelimiter(b) {
+			v, b, err = p.parseMultilineBasicString(b)
+		} else {
+			v, b, err = p.parseBasicString(b)
+		}
+		if err == nil {
+			p.builder.StringValue(v)
+		}
+		return b, err
+	case '\'':
+		var v []byte
+		if scanFollowsMultilineLiteralStringDelimiter(b) {
+			v, b, err = p.parseMultilineLiteralString(b)
+		} else {
+			v, b, err = p.parseLiteralString(b)
+		}
+		if err == nil {
+			p.builder.StringValue(v)
+		}
+		return b, err
+	case 't':
+		if !scanFollowsTrue(b) {
+			return nil, fmt.Errorf("expected 'true'")
+		}
+		p.builder.BoolValue(true)
+		return b[4:], nil
+	case 'f':
+		if !scanFollowsFalse(b) {
+			return nil, fmt.Errorf("expected 'false'")
+		}
+		p.builder.BoolValue(false)
+		return b[5:], nil
+	case '[':
+		return p.parseValArray(b)
+	case '{':
+		return p.parseInlineTable(b)
+
+	// TODO date-time
+
+	// TODO float
+
+	// TODO integer
+	default:
+		return nil, fmt.Errorf("unexpected char")
+	}
+}
+
+func (p parser) parseLiteralString(b []byte) ([]byte, []byte, error) {
+	v, rest, err := scanLiteralString(b)
+	if err != nil {
+		return nil, nil, err
+	}
+	return v[1 : len(v)-1], rest, nil
+}
+
+func (p parser) parseInlineTable(b []byte) ([]byte, error) {
+	//inline-table = inline-table-open [ inline-table-keyvals ] inline-table-close
+	//inline-table-open  = %x7B ws     ; {
+	//inline-table-close = ws %x7D     ; }
+	//inline-table-sep   = ws %x2C ws  ; , Comma
+	//inline-table-keyvals = keyval [ inline-table-sep inline-table-keyvals ]
+
+	b = b[1:]
+
+	first := true
+	var err error
+	for len(b) > 0 {
+		b = p.parseWhitespace(b)
+		if b[0] == '}' {
+			break
+		}
+
+		if !first {
+			b, err = expect(',', b)
+			if err != nil {
+				return nil, err
+			}
+			b = p.parseWhitespace(b)
+		}
+		b, err = p.parseKeyval(b)
+		if err != nil {
+			return nil, err
+		}
+
+		first = false
+	}
+	return expect('}', b)
+}
+
+func (p parser) parseValArray(b []byte) ([]byte, error) {
+	//array = array-open [ array-values ] ws-comment-newline array-close
+	//array-open =  %x5B ; [
+	//array-close = %x5D ; ]
+	//array-values =  ws-comment-newline val ws-comment-newline array-sep array-values
+	//array-values =/ ws-comment-newline val ws-comment-newline [ array-sep ]
+	//array-sep = %x2C  ; , Comma
+	//ws-comment-newline = *( wschar / [ comment ] newline )
+
+	p.builder.ArrayBegin()
+	defer p.builder.ArrayEnd()
+
+	b = b[1:]
+
+	first := true
+	var err error
+	for len(b) > 0 {
+		b, err = p.parseOptionalWhitespaceCommentNewline(b)
+		if err != nil {
+			return nil, err
+		}
+
+		if len(b) == 0 {
+			return nil, unexpectedCharacter{b: b}
+		}
+
+		if b[0] == ']' {
+			break
+		}
+		if b[0] == ',' {
+			if first {
+				return nil, fmt.Errorf("array cannot start with comma")
+			}
+			b = b[1:]
+			b, err = p.parseOptionalWhitespaceCommentNewline(b)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		b, err = p.parseVal(b)
+		if err != nil {
+			return nil, err
+		}
+		b, err = p.parseOptionalWhitespaceCommentNewline(b)
+		if err != nil {
+			return nil, err
+		}
+		first = false
+	}
+
+	return expect(']', b)
+}
+
+func (p parser) parseOptionalWhitespaceCommentNewline(b []byte) ([]byte, error) {
+	var err error
+	b = p.parseWhitespace(b)
+	if len(b) > 0 && b[0] == '#' {
+		_, b, err = scanComment(b)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if len(b) > 0 && (b[0] == '\n' || b[0] == '\r') {
+		b, err = p.parseNewline(b)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return b, nil
+}
+
+func (p parser) parseMultilineLiteralString(b []byte) ([]byte, []byte, error) {
+	token, rest, err := scanMultilineLiteralString(b)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	i := 3
+
+	// skip the immediate new line
+	if token[i] == '\n' {
+		i++
+	} else if token[i] == '\r' && token[i+1] == '\n' {
+		i += 2
+	}
+
+	return token[i : len(b)-3], rest, err
+}
+
+func (p parser) parseMultilineBasicString(b []byte) ([]byte, []byte, error) {
+	//ml-basic-string = ml-basic-string-delim [ newline ] ml-basic-body
+	//ml-basic-string-delim
+	//ml-basic-string-delim = 3quotation-mark
+	//ml-basic-body = *mlb-content *( mlb-quotes 1*mlb-content ) [ mlb-quotes ]
+	//
+	//mlb-content = mlb-char / newline / mlb-escaped-nl
+	//mlb-char = mlb-unescaped / escaped
+	//mlb-quotes = 1*2quotation-mark
+	//mlb-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
+	//mlb-escaped-nl = escape ws newline *( wschar / newline )
+
+	token, rest, err := scanMultilineBasicString(b)
+	if err != nil {
+		return nil, nil, err
+	}
+	var builder bytes.Buffer
+
+	i := 3
+
+	// skip the immediate new line
+	if token[i] == '\n' {
+		i++
+	} else if token[i] == '\r' && token[i+1] == '\n' {
+		i += 2
+	}
+
+	// The scanner ensures that the token starts and ends with quotes and that
+	// escapes are balanced.
+	for ; i < len(token)-3; i++ {
+		c := token[i]
+		if c == '\\' {
+			// When the last non-whitespace character on a line is an unescaped \,
+			// it will be trimmed along with all whitespace (including newlines) up
+			// to the next non-whitespace character or closing delimiter.
+			if token[i+1] == '\n' || (token[i+1] == '\r' && token[i+2] == '\n') {
+				i++ // skip the \
+				for ; i < len(token)-3; i++ {
+					c := token[i]
+					if !(c == '\n' || c == '\r' || c == ' ' || c == '\t') {
+						break
+					}
+				}
+				continue
+			}
+
+			// handle escaping
+			i++
+			c = token[i]
+			switch c {
+			case '"', '\\':
+				builder.WriteByte(c)
+			case 'b':
+				builder.WriteByte('\b')
+			case 'f':
+				builder.WriteByte('\f')
+			case 'n':
+				builder.WriteByte('\n')
+			case 'r':
+				builder.WriteByte('\r')
+			case 't':
+				builder.WriteByte('\t')
+			case 'u':
+				x, err := hexToString(token[i+3:len(token)-3], 4)
+				if err != nil {
+					return nil, nil, err
+				}
+				builder.WriteString(x)
+				i += 4
+			case 'U':
+				x, err := hexToString(token[i+3:len(token)-3], 8)
+				if err != nil {
+					return nil, nil, err
+				}
+				builder.WriteString(x)
+				i += 8
+			default:
+				return nil, nil, fmt.Errorf("invalid escaped character: %#U", c)
+			}
+		} else {
+			builder.WriteByte(c)
+		}
+	}
+
+	return builder.Bytes(), rest, nil
+}
+
+func (p parser) parseKey(b []byte) ([]byte, error) {
+	//key = simple-key / dotted-key
+	//simple-key = quoted-key / unquoted-key
+	//
+	//unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
+	//quoted-key = basic-string / literal-string
+	//dotted-key = simple-key 1*( dot-sep simple-key )
+	//
+	//dot-sep   = ws %x2E ws  ; . Period
+
+	b, err := p.parseSimpleKey(b)
+	if err != nil {
+		return nil, err
+	}
+
+	for {
+		b = p.parseWhitespace(b)
+		if len(b) > 0 && b[0] == '.' {
+			b, err = expect('.', b)
+			if err != nil {
+				return nil, err
+			}
+			b = p.parseWhitespace(b)
+			b, err = p.parseSimpleKey(b)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			break
+		}
+	}
+
+	return b, nil
+}
+
+func (p parser) parseSimpleKey(b []byte) (rest []byte, err error) {
+	//simple-key = quoted-key / unquoted-key
+	//unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
+	//quoted-key = basic-string / literal-string
+
+	if len(b) == 0 {
+		return nil, unexpectedCharacter{b: b}
+	}
+
+	var v []byte
+	if b[0] == '\'' {
+		v, rest, err = scanLiteralString(b)
+	} else if b[0] == '"' {
+		v, rest, err = p.parseBasicString(b)
+	} else if isUnquotedKeyChar(b[0]) {
+		v, rest, err = scanUnquotedKey(b)
+	} else {
+		return nil, unexpectedCharacter{b: b}
+	}
+	p.builder.SimpleKey(v)
+	return
+}
+
+func (p parser) parseBasicString(b []byte) ([]byte, []byte, error) {
+	//basic-string = quotation-mark *basic-char quotation-mark
+	//quotation-mark = %x22            ; "
+	//basic-char = basic-unescaped / escaped
+	//basic-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
+	//escaped = escape escape-seq-char
+	//escape-seq-char =  %x22         ; "    quotation mark  U+0022
+	//escape-seq-char =/ %x5C         ; \    reverse solidus U+005C
+	//escape-seq-char =/ %x62         ; b    backspace       U+0008
+	//escape-seq-char =/ %x66         ; f    form feed       U+000C
+	//escape-seq-char =/ %x6E         ; n    line feed       U+000A
+	//escape-seq-char =/ %x72         ; r    carriage return U+000D
+	//escape-seq-char =/ %x74         ; t    tab             U+0009
+	//escape-seq-char =/ %x75 4HEXDIG ; uXXXX                U+XXXX
+	//escape-seq-char =/ %x55 8HEXDIG ; UXXXXXXXX            U+XXXXXXXX
+
+	token, rest, err := scanBasicString(b)
+	if err != nil {
+		return nil, nil, err
+	}
+	var builder bytes.Buffer
+
+	// The scanner ensures that the token starts and ends with quotes and that
+	// escapes are balanced.
+	for i := 1; i < len(token)-1; i++ {
+		c := token[i]
+		if c == '\\' {
+			i++
+			c = token[i]
+			switch c {
+			case '"', '\\':
+				builder.WriteByte(c)
+			case 'b':
+				builder.WriteByte('\b')
+			case 'f':
+				builder.WriteByte('\f')
+			case 'n':
+				builder.WriteByte('\n')
+			case 'r':
+				builder.WriteByte('\r')
+			case 't':
+				builder.WriteByte('\t')
+			case 'u':
+				x, err := hexToString(token[i+1:len(token)-1], 4)
+				if err != nil {
+					return nil, nil, err
+				}
+				builder.WriteString(x)
+				i += 4
+			case 'U':
+				x, err := hexToString(token[i+1:len(token)-1], 8)
+				if err != nil {
+					return nil, nil, err
+				}
+				builder.WriteString(x)
+				i += 8
+			default:
+				return nil, nil, fmt.Errorf("invalid escaped character: %#U", c)
+			}
+		} else {
+			builder.WriteByte(c)
+		}
+	}
+
+	return builder.Bytes(), rest, nil
+}
+
+func hexToString(b []byte, length int) (string, error) {
+	if len(b) < length {
+		return "", fmt.Errorf("unicode point needs %d hex characters", length)
+	}
+	// TODO: slow
+	b, err := hex.DecodeString(string(b[:length]))
+	if err != nil {
+		return "", err
+	}
+	return string(b), nil
+}
+
+func (p parser) parseWhitespace(b []byte) []byte {
+	//ws = *wschar
+	//wschar =  %x20  ; Space
+	//wschar =/ %x09  ; Horizontal tab
+
+	_, rest := scanWhitespace(b)
+	return rest
+}
+
+func expect(x byte, b []byte) ([]byte, error) {
+	if len(b) == 0 || b[0] != x {
+		return nil, unexpectedCharacter{r: x, b: b}
+	}
+	return b[1:], nil
+}
+
+type unexpectedCharacter struct {
+	r byte
+	b []byte
+}
+
+func (u unexpectedCharacter) Error() string {
+	if len(u.b) == 0 {
+		return fmt.Sprintf("expected %#U, not EOF", u.r)
+
+	}
+	return fmt.Sprintf("expected %#U, not %#U", u.r, u.b[0])
+}