parser: introduce SplitCommaArray to splits comma separated strings

removing whitespace and respecting quoted literals.

Signed-off-by: Alejandro Mery <amery@jpi.io>

parser/comma_array.go

@@ -0,0 +1,88 @@
+package parser
+
+import (
+	"strings"
+
+	"asciigoat.org/core/lexer"
+)
+
+type commaArrayParser struct {
+	TextParser
+
+	out []string
+}
+
+func (p *commaArrayParser) lexStart() (lexer.StateFn, error) {
+	for {
+		r, _, err := p.ReadRune()
+		switch {
+		case err != nil:
+			// EOF
+			return nil, err
+		case r == RuneQuotes:
+			// Quoted Value
+			return p.lexQuotedString, nil
+		case IsNewLine(r):
+			// new lines are acceptable when parsing a string for
+			// comma delimited arrays. but make sure we discard it
+			// complete
+			p.UnreadRune()
+			p.AcceptNewLine()
+			p.Discard()
+		case lexer.IsSpace(r):
+			// discard whitespace outside quotes
+			p.Discard()
+		default:
+			p.UnreadRune()
+			return p.lexWord, nil
+		}
+	}
+}
+
+func (p *commaArrayParser) lexWord() (lexer.StateFn, error) {
+	for {
+		r, _, err := p.ReadRune()
+		switch {
+		case err != nil:
+			// done. store what we got and move on
+			_, s := p.Emit()
+			p.out = append(p.out, s)
+			return nil, err
+		case r == ',':
+			// done
+			_, s := p.Emit()
+			// remove comma, trim and append to output
+			s = strings.TrimRightFunc(s[:len(s)-1], IsSpace)
+			p.out = append(p.out, s)
+			return p.lexStart, nil
+		}
+	}
+}
+
+func (p *commaArrayParser) lexQuotedString() (lexer.StateFn, error) {
+	s, err := lexQuotedString(&p.TextParser)
+	if err != nil {
+		return nil, err
+	}
+
+	p.Discard()
+	p.out = append(p.out, s)
+	return p.lexStart, nil
+}
+
+func (p *commaArrayParser) Run() ([]string, error) {
+	err := lexer.Run(p.lexStart)
+
+	return p.out, err
+}
+
+// SplitCommaArray splits comma separated strings, removing whitespace
+// and respecting quoted literals.
+func SplitCommaArray(s string) ([]string, error) {
+	if s != "" {
+		var p commaArrayParser
+		p.InitString(s)
+		return p.Run()
+	}
+	return nil, nil
+}