1 files changed, 107 insertions, 0 deletions
diff --git a/literals.go b/literals.go
new file mode 100644
index 0000000..241dd93
--- /dev/null
+++ b/literals.go
@@ -0,0 +1,107 @@
+package goparsify
+
+import (
+	"bytes"
+	"unicode/utf8"
+)
+
+func StringLit(allowedQuotes string) Parser {
+	return NewParser("string", func(ps *State) Node {
+		ps.AutoWS()
+
+		for i := 0; i < len(allowedQuotes); i++ {
+			if ps.Input[ps.Pos] == allowedQuotes[i] {
+
+			}
+		}
+		if !stringContainsByte(allowedQuotes, ps.Input[ps.Pos]) {
+			ps.ErrorHere(allowedQuotes)
+			return Node{}
+		}
+		quote := ps.Input[ps.Pos]
+
+		var end int = ps.Pos + 1
+
+		inputLen := len(ps.Input)
+		var buf *bytes.Buffer
+
+		for end < inputLen {
+			switch ps.Input[end] {
+			case '\\':
+				if end+1 >= inputLen {
+					ps.ErrorHere(string(quote))
+					return Node{}
+				}
+
+				if buf == nil {
+					buf = bytes.NewBufferString(ps.Input[ps.Pos+1 : end])
+				}
+
+				c := ps.Input[end+1]
+				if c == 'u' {
+					if end+6 >= inputLen {
+						ps.Error.Expected = "[a-f0-9]{4}"
+						ps.Error.pos = end + 2
+						return Node{}
+					}
+
+					r, ok := unhex(ps.Input[end+2 : end+6])
+					if !ok {
+						ps.Error.Expected = "[a-f0-9]"
+						ps.Error.pos = end + 2
+						return Node{}
+					}
+					buf.WriteRune(r)
+					end += 6
+				} else {
+					buf.WriteByte(c)
+					end += 2
+				}
+			case quote:
+				if buf == nil {
+					result := ps.Input[ps.Pos+1 : end]
+					ps.Pos = end + 1
+					return Node{Token: result}
+				}
+				ps.Pos = end + 1
+				return Node{Token: buf.String()}
+			default:
+				r, w := utf8.DecodeRuneInString(ps.Input[end:])
+				end += w
+				if buf != nil {
+					buf.WriteRune(r)
+				}
+			}
+		}
+
+		ps.ErrorHere(string(quote))
+		return Node{}
+	})
+}
+
+func stringContainsByte(s string, b byte) bool {
+	for i := 0; i < len(s); i++ {
+		if b == s[i] {
+			return true
+		}
+	}
+	return false
+}
+
+func unhex(b string) (v rune, ok bool) {
+	for _, c := range b {
+		v <<= 4
+		switch {
+		case '0' <= c && c <= '9':
+			v |= c - '0'
+		case 'a' <= c && c <= 'f':
+			v |= c - 'a' + 10
+		case 'A' <= c && c <= 'F':
+			v |= c - 'A' + 10
+		default:
+			return 0, false
+		}
+	}
+
+	return v, true
+}