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Diffstat (limited to 'config/parser.go')
-rw-r--r--config/parser.go496
1 files changed, 496 insertions, 0 deletions
diff --git a/config/parser.go b/config/parser.go
new file mode 100644
index 00000000..edaf1944
--- /dev/null
+++ b/config/parser.go
@@ -0,0 +1,496 @@
+package config
+
+import (
+ "bufio"
+ "bytes"
+ "errors"
+ "fmt"
+ "io"
+ "strings"
+)
+
+type configParser struct {
+ reader *bufio.Reader
+ lineNum int
+ currentSection string
+ currentSubsec string
+ peeked byte
+ hasPeeked bool
+}
+
+func (p *configParser) parse() (*Config, error) {
+ cfg := &Config{}
+
+ err := p.skipBOM()
+ if err != nil {
+ return nil, err
+ }
+
+ for {
+ ch, err := p.nextChar()
+ if errors.Is(err, io.EOF) {
+ break
+ }
+
+ if err != nil {
+ return nil, err
+ }
+
+ // Skip leading whitespace between entries.
+ if isWhitespace(ch) {
+ continue
+ }
+
+ // Comments
+ if ch == '#' || ch == ';' {
+ err := p.skipToEOL()
+ if err != nil && !errors.Is(err, io.EOF) {
+ return nil, err
+ }
+
+ continue
+ }
+
+ // Section header
+ if ch == '[' {
+ err := p.parseSection()
+ if err != nil {
+ return nil, fmt.Errorf("furgit: config: line %d: %w", p.lineNum, err)
+ }
+
+ continue
+ }
+
+ // Key-value pair
+ if isLetter(ch) {
+ p.unreadChar(ch)
+
+ err := p.parseKeyValue(cfg)
+ if err != nil {
+ return nil, fmt.Errorf("furgit: config: line %d: %w", p.lineNum, err)
+ }
+
+ continue
+ }
+
+ return nil, fmt.Errorf("furgit: config: line %d: unexpected character %q", p.lineNum, ch)
+ }
+
+ return cfg, nil
+}
+
+func (p *configParser) nextChar() (byte, error) {
+ if p.hasPeeked {
+ p.hasPeeked = false
+
+ return p.peeked, nil
+ }
+
+ ch, err := p.reader.ReadByte()
+ if err != nil {
+ return 0, err
+ }
+
+ if ch == '\r' {
+ next, err := p.reader.ReadByte()
+ if err == nil && next == '\n' {
+ ch = '\n'
+ } else if err == nil {
+ // Weird but ok
+ _ = p.reader.UnreadByte()
+ }
+ }
+
+ if ch == '\n' {
+ p.lineNum++
+ }
+
+ return ch, nil
+}
+
+func (p *configParser) unreadChar(ch byte) {
+ p.peeked = ch
+
+ p.hasPeeked = true
+ if ch == '\n' && p.lineNum > 1 {
+ p.lineNum--
+ }
+}
+
+func (p *configParser) skipBOM() error {
+ first, err := p.reader.ReadByte()
+ if errors.Is(err, io.EOF) {
+ return nil
+ }
+
+ if err != nil {
+ return err
+ }
+
+ if first != 0xef {
+ _ = p.reader.UnreadByte()
+
+ return nil
+ }
+
+ second, err := p.reader.ReadByte()
+ if err != nil {
+ if errors.Is(err, io.EOF) {
+ _ = p.reader.UnreadByte()
+
+ return nil
+ }
+
+ return err
+ }
+
+ third, err := p.reader.ReadByte()
+ if err != nil {
+ if errors.Is(err, io.EOF) {
+ _ = p.reader.UnreadByte()
+ _ = p.reader.UnreadByte()
+
+ return nil
+ }
+
+ return err
+ }
+
+ if second == 0xbb && third == 0xbf {
+ return nil
+ }
+
+ _ = p.reader.UnreadByte()
+ _ = p.reader.UnreadByte()
+ _ = p.reader.UnreadByte()
+
+ return nil
+}
+
+func (p *configParser) skipToEOL() error {
+ for {
+ ch, err := p.nextChar()
+ if err != nil {
+ return err
+ }
+
+ if ch == '\n' {
+ return nil
+ }
+ }
+}
+
+func (p *configParser) parseSection() error {
+ var name bytes.Buffer
+
+ for {
+ ch, err := p.nextChar()
+ if err != nil {
+ return errors.New("unexpected EOF in section header")
+ }
+
+ if ch == ']' {
+ section := name.String()
+ if !isValidSection(section) {
+ return fmt.Errorf("invalid section name: %q", section)
+ }
+
+ p.currentSection = strings.ToLower(section)
+ p.currentSubsec = ""
+
+ return nil
+ }
+
+ if isWhitespace(ch) {
+ return p.parseExtendedSection(&name)
+ }
+
+ if !isKeyChar(ch) && ch != '.' {
+ return fmt.Errorf("invalid character in section name: %q", ch)
+ }
+
+ name.WriteByte(toLower(ch))
+ }
+}
+
+func (p *configParser) parseExtendedSection(sectionName *bytes.Buffer) error {
+ for {
+ ch, err := p.nextChar()
+ if err != nil {
+ return errors.New("unexpected EOF in section header")
+ }
+
+ if !isWhitespace(ch) {
+ if ch != '"' {
+ return errors.New("expected quote after section name")
+ }
+
+ break
+ }
+ }
+
+ var subsec bytes.Buffer
+
+ for {
+ ch, err := p.nextChar()
+ if err != nil {
+ return errors.New("unexpected EOF in subsection")
+ }
+
+ if ch == '\n' {
+ return errors.New("newline in subsection")
+ }
+
+ if ch == '"' {
+ break
+ }
+
+ if ch == '\\' {
+ next, err := p.nextChar()
+ if err != nil {
+ return errors.New("unexpected EOF after backslash in subsection")
+ }
+
+ if next == '\n' {
+ return errors.New("newline after backslash in subsection")
+ }
+
+ subsec.WriteByte(next)
+ } else {
+ subsec.WriteByte(ch)
+ }
+ }
+
+ ch, err := p.nextChar()
+ if err != nil {
+ return errors.New("unexpected EOF after subsection")
+ }
+
+ if ch != ']' {
+ return fmt.Errorf("expected ']' after subsection, got %q", ch)
+ }
+
+ section := sectionName.String()
+ if !isValidSection(section) {
+ return fmt.Errorf("invalid section name: %q", section)
+ }
+
+ p.currentSection = strings.ToLower(section)
+ p.currentSubsec = subsec.String()
+
+ return nil
+}
+
+func (p *configParser) parseKeyValue(cfg *Config) error {
+ if p.currentSection == "" {
+ return errors.New("key-value pair before any section header")
+ }
+
+ var key bytes.Buffer
+
+ for {
+ ch, err := p.nextChar()
+ if errors.Is(err, io.EOF) {
+ break
+ }
+
+ if err != nil {
+ return err
+ }
+
+ if ch == '=' || ch == '\n' || isSpace(ch) {
+ p.unreadChar(ch)
+
+ break
+ }
+
+ if !isKeyChar(ch) {
+ return fmt.Errorf("invalid character in key: %q", ch)
+ }
+
+ key.WriteByte(toLower(ch))
+ }
+
+ keyStr := key.String()
+ if len(keyStr) == 0 {
+ return errors.New("empty key name")
+ }
+
+ if !isLetter(keyStr[0]) {
+ return errors.New("key must start with a letter")
+ }
+
+ for {
+ ch, err := p.nextChar()
+ if errors.Is(err, io.EOF) {
+ cfg.entries = append(cfg.entries, ConfigEntry{
+ Section: p.currentSection,
+ Subsection: p.currentSubsec,
+ Key: keyStr,
+ Kind: ValueValueless,
+ Value: "",
+ })
+
+ return nil
+ }
+
+ if err != nil {
+ return err
+ }
+
+ if ch == '\n' {
+ cfg.entries = append(cfg.entries, ConfigEntry{
+ Section: p.currentSection,
+ Subsection: p.currentSubsec,
+ Key: keyStr,
+ Kind: ValueValueless,
+ Value: "",
+ })
+
+ return nil
+ }
+
+ if ch == '#' || ch == ';' {
+ err := p.skipToEOL()
+ if err != nil && !errors.Is(err, io.EOF) {
+ return err
+ }
+
+ cfg.entries = append(cfg.entries, ConfigEntry{
+ Section: p.currentSection,
+ Subsection: p.currentSubsec,
+ Key: keyStr,
+ Kind: ValueValueless,
+ Value: "",
+ })
+
+ return nil
+ }
+
+ if ch == '=' {
+ break
+ }
+
+ if !isSpace(ch) {
+ return fmt.Errorf("unexpected character after key: %q", ch)
+ }
+ }
+
+ value, err := p.parseValue()
+ if err != nil {
+ return err
+ }
+
+ cfg.entries = append(cfg.entries, ConfigEntry{
+ Section: p.currentSection,
+ Subsection: p.currentSubsec,
+ Key: keyStr,
+ Kind: ValueString,
+ Value: value,
+ })
+
+ return nil
+}
+
+func (p *configParser) parseValue() (string, error) {
+ var (
+ value bytes.Buffer
+ inQuote bool
+ inComment bool
+ )
+
+ trimLen := 0
+
+ for {
+ ch, err := p.nextChar()
+ if errors.Is(err, io.EOF) {
+ if inQuote {
+ return "", errors.New("unexpected EOF in quoted value")
+ }
+
+ if trimLen > 0 {
+ return truncateAtNUL(value.String()[:trimLen]), nil
+ }
+
+ return truncateAtNUL(value.String()), nil
+ }
+
+ if err != nil {
+ return "", err
+ }
+
+ if ch == '\n' {
+ if inQuote {
+ return "", errors.New("newline in quoted value")
+ }
+
+ if trimLen > 0 {
+ return truncateAtNUL(value.String()[:trimLen]), nil
+ }
+
+ return truncateAtNUL(value.String()), nil
+ }
+
+ if inComment {
+ continue
+ }
+
+ if isWhitespace(ch) && !inQuote {
+ if trimLen == 0 && value.Len() > 0 {
+ trimLen = value.Len()
+ }
+
+ if value.Len() > 0 {
+ value.WriteByte(ch)
+ }
+
+ continue
+ }
+
+ if !inQuote && (ch == '#' || ch == ';') {
+ inComment = true
+
+ continue
+ }
+
+ if trimLen > 0 {
+ trimLen = 0
+ }
+
+ if ch == '\\' {
+ next, err := p.nextChar()
+ if errors.Is(err, io.EOF) {
+ return "", errors.New("unexpected EOF after backslash")
+ }
+
+ if err != nil {
+ return "", err
+ }
+
+ switch next {
+ case '\n':
+ continue
+ case 'n':
+ value.WriteByte('\n')
+ case 't':
+ value.WriteByte('\t')
+ case 'b':
+ value.WriteByte('\b')
+ case '\\', '"':
+ value.WriteByte(next)
+ default:
+ return "", fmt.Errorf("invalid escape sequence: \\%c", next)
+ }
+
+ continue
+ }
+
+ if ch == '"' {
+ inQuote = !inQuote
+
+ continue
+ }
+
+ value.WriteByte(ch)
+ }
+}
generated by cgit v1.3.1-10-gc9f91 (git 2.54.0) at 2026-05-25 14:02:56 +0000