feat/schema: add lexer

schema/util/litconv.go

@@ -0,0 +1,101 @@
+// Code generated by gocc; DO NOT EDIT.
+
+package util
+
+import (
+	"fmt"
+	"strconv"
+	"unicode"
+	"unicode/utf8"
+)
+
+// Interface.
+
+// RuneValue will convert the literal value of a scanned token to a rune.
+func RuneValue(lit []byte) rune {
+	if lit[1] == '\\' {
+		return escapeCharVal(lit)
+	}
+	r, size := utf8.DecodeRune(lit[1:])
+	if size != len(lit)-2 {
+		panic(fmt.Sprintf("Error decoding rune. Lit: %s, rune: %d, size%d\n", lit, r, size))
+	}
+	return r
+}
+
+// UintValue will attempt to parse a byte-slice as a signed base-10 64-bit integer.
+func IntValue(lit []byte) (int64, error) {
+	return strconv.ParseInt(string(lit), 10, 64)
+}
+
+// UintValue will attempt to parse a byte-slice as an unsigned base-10 64-bit integer.
+func UintValue(lit []byte) (uint64, error) {
+	return strconv.ParseUint(string(lit), 10, 64)
+}
+
+// Helpers.
+func escapeCharVal(lit []byte) rune {
+	var i, base, max uint32
+	offset := 2
+	switch lit[offset] {
+	case 'a':
+		return '\a'
+	case 'b':
+		return '\b'
+	case 'f':
+		return '\f'
+	case 'n':
+		return '\n'
+	case 'r':
+		return '\r'
+	case 't':
+		return '\t'
+	case 'v':
+		return '\v'
+	case '\\':
+		return '\\'
+	case '\'':
+		return '\''
+	case '0', '1', '2', '3', '4', '5', '6', '7':
+		i, base, max = 3, 8, 255
+	case 'x':
+		i, base, max = 2, 16, 255
+		offset++
+	case 'u':
+		i, base, max = 4, 16, unicode.MaxRune
+		offset++
+	case 'U':
+		i, base, max = 8, 16, unicode.MaxRune
+		offset++
+	default:
+		panic(fmt.Sprintf("Error decoding character literal: %s\n", lit))
+	}
+
+	var x uint32
+	for ; i > 0 && offset < len(lit)-1; i-- {
+		ch, size := utf8.DecodeRune(lit[offset:])
+		offset += size
+		d := uint32(digitVal(ch))
+		if d >= base {
+			panic(fmt.Sprintf("charVal(%s): illegal character (%c) in escape sequence. size=%d, offset=%d", lit, ch, size, offset))
+		}
+		x = x*base + d
+	}
+	if x > max || 0xD800 <= x && x < 0xE000 {
+		panic(fmt.Sprintf("Error decoding escape char value. Lit:%s, offset:%d, escape sequence is invalid Unicode code point\n", lit, offset))
+	}
+
+	return rune(x)
+}
+
+func digitVal(ch rune) int {
+	switch {
+	case '0' <= ch && ch <= '9':
+		return int(ch) - '0'
+	case 'a' <= ch && ch <= 'f':
+		return int(ch) - 'a' + 10
+	case 'A' <= ch && ch <= 'F':
+		return int(ch) - 'A' + 10
+	}
+	return 16 // larger than any legal digit val
+}