initial

1 files changed, 50 insertions, 0 deletions

diff --git a/scanners.go b/scanners.go
new file mode 100644
index 0000000..323e7a1
--- /dev/null
+++ b/scanners.go
@@ -0,0 +1,50 @@
+package lexpr
+
+import (
+	"strings"
+)
+
+const (
+	digits = "0123456789"
+	alpha  = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM"
+	chars  = "+-*/=<>@&|:!."
+)
+
+// scanNumber simplest scanner that accepts decimal int and float.
+func scanNumber(l *lex) bool {
+	l.acceptWhile(digits, false)
+	if l.atStart() {
+		// not found any digit
+		return false
+	}
+	l.accept(".")
+	l.acceptWhile(digits, false)
+	return !l.atStart()
+}
+
+// scanWord returns true if next input token contains alphanum sequence that not starts from digit and not contains.
+// spaces or special characters.
+func scanWord(l *lex) bool {
+	if !l.accept(alpha) {
+		return false
+	}
+	l.acceptWhile(alpha+digits, false)
+	return true
+}
+
+func scanOps(l *lex) bool {
+	return l.acceptWhile(chars, false)
+}
+
+// scanQuotedString returns true if next input tokens is quoted string. Can be used with any type of quotes.
+func scanQuotedString(l *lex, quote string) bool {
+	start := l.pos
+	if !strings.ContainsRune(quote, l.next()) {
+		l.pos = start
+		return false
+	}
+	if l.acceptWhileNot(quote, true) {
+		l.next()
+	}
+	return !l.atStart()
+}