v0.1.0 initial commit

2026-08-06 10:18:22 -04:00
commit 28e42523e1
31 changed files with 5055 additions and 0 deletions
@@ -0,0 +1,212 @@
+package logfile
+
+import (
+	"bytes"
+	"strconv"
+)
+
+// JSON token kinds.
+const (
+	KNone byte = 0
+	KStr  byte = 's'
+	KNum  byte = 'n'
+	KBool byte = 'b'
+	KNull byte = 'z'
+	KObj  byte = 'o'
+	KArr  byte = 'a'
+)
+
+func skipSpace(b []byte, i int) int {
+	for i < len(b) && (b[i] == ' ' || b[i] == '\t' || b[i] == '\r' || b[i] == '\n') {
+		i++
+	}
+	return i
+}
+
+func isNumByte(c byte) bool {
+	return c == '-' || c == '+' || c == '.' || c == 'e' || c == 'E' || (c >= '0' && c <= '9')
+}
+
+// scanString returns the index past the closing quote; i indexes the opener.
+func scanString(b []byte, i int) (int, bool) {
+	for i++; i < len(b); i++ {
+		switch b[i] {
+		case '\\':
+			i++
+		case '"':
+			return i + 1, true
+		}
+	}
+	return i, false
+}
+
+// scanValue returns the end index and kind of the value starting at i.
+func scanValue(b []byte, i int) (int, byte, bool) {
+	if i >= len(b) {
+		return i, KNone, false
+	}
+	switch c := b[i]; c {
+	case '"':
+		e, ok := scanString(b, i)
+		return e, KStr, ok
+
+	case '{', '[':
+		opener, closer, kind := byte('{'), byte('}'), KObj
+		if c == '[' {
+			opener, closer, kind = '[', ']', KArr
+		}
+		depth := 0
+		for i < len(b) {
+			ch := b[i]
+			if ch == '"' {
+				e, ok := scanString(b, i)
+				if !ok {
+					return e, kind, false
+				}
+				i = e
+				continue
+			}
+			if ch == opener {
+				depth++
+			} else if ch == closer {
+				depth--
+				if depth == 0 {
+					return i + 1, kind, true
+				}
+			}
+			i++
+		}
+		return i, kind, false
+
+	case 't', 'f', 'n':
+		kind := KBool
+		if c == 'n' {
+			kind = KNull
+		}
+		for i < len(b) && b[i] >= 'a' && b[i] <= 'z' {
+			i++
+		}
+		return i, kind, true
+
+	default:
+		for i < len(b) && isNumByte(b[i]) {
+			i++
+		}
+		return i, KNum, true
+	}
+}
+
+// eachField calls fn for each member of the object at i, which must index '{'.
+// fn returning false stops iteration. Reports whether the object is well formed.
+func eachField(b []byte, i int, fn func(key, val []byte, kind byte) bool) bool {
+	if i >= len(b) || b[i] != '{' {
+		return false
+	}
+	i = skipSpace(b, i+1)
+	if i < len(b) && b[i] == '}' {
+		return true
+	}
+	for i < len(b) {
+		if b[i] != '"' {
+			return false
+		}
+		ke, ok := scanString(b, i)
+		if !ok {
+			return false
+		}
+		key := b[i+1 : ke-1]
+
+		i = skipSpace(b, ke)
+		if i >= len(b) || b[i] != ':' {
+			return false
+		}
+		i = skipSpace(b, i+1)
+
+		vs := i
+		ve, kind, ok := scanValue(b, i)
+		if !ok {
+			return false
+		}
+		if !fn(key, b[vs:ve], kind) {
+			return true
+		}
+
+		i = skipSpace(b, ve)
+		if i >= len(b) {
+			return false
+		}
+		switch b[i] {
+		case ',':
+			i = skipSpace(b, i+1)
+		case '}':
+			return true
+		default:
+			return false
+		}
+	}
+	return false
+}
+
+// strTok returns the undecoded content of a string token.
+func strTok(tok []byte) []byte {
+	if len(tok) < 2 {
+		return nil
+	}
+	return tok[1 : len(tok)-1]
+}
+
+// unquote returns the content of a string token, decoding escapes only when present.
+func unquote(tok []byte) string {
+	in := strTok(tok)
+	if bytes.IndexByte(in, '\\') < 0 {
+		return string(in)
+	}
+	if s, err := strconv.Unquote(string(tok)); err == nil {
+		return s
+	}
+	return string(in)
+}
+
+// parseUint32 parses a leading decimal run, saturating at the type maximum.
+func parseUint32(b []byte) uint32 {
+	var v uint64
+	for _, c := range b {
+		if c < '0' || c > '9' {
+			break
+		}
+		v = v*10 + uint64(c-'0')
+		if v > 0xffffffff {
+			return 0xffffffff
+		}
+	}
+	return uint32(v)
+}
+
+// parseInt64 parses a complete decimal integer token without allocating.
+func parseInt64(b []byte) (int64, bool) {
+	if len(b) == 0 {
+		return 0, false
+	}
+	i, neg := 0, false
+	if b[0] == '-' || b[0] == '+' {
+		neg = b[0] == '-'
+		i++
+	}
+	if i >= len(b) {
+		return 0, false
+	}
+	var v int64
+	for ; i < len(b); i++ {
+		if b[i] < '0' || b[i] > '9' {
+			return 0, false
+		}
+		v = v*10 + int64(b[i]-'0')
+		if v < 0 {
+			return 0, false
+		}
+	}
+	if neg {
+		v = -v
+	}
+	return v, true
+}