_future

1. Fix index, including both start and end. So Literal[start:end+1] will
be a valid part.

2. Replace any with string, add file param type

3. Start of making the evaluator, starting with regexp for param types
(these expression can be changed or/and overriden by user later on)


Former-commit-id: ab95265f953dadbf84170b543e1ff8840f9c4a14

_future/ipel/evaluator/evaluator.go

@@ -0,0 +1,27 @@
+package evaluator
+
+import (
+	"fmt"
+	"regexp"
+)
+
+// final evaluator signature for both param types and param funcs
+type ParamEvaluator func(paramValue string) bool
+
+func NewParamEvaluatorFromRegexp(expr string) (ParamEvaluator, error) {
+	if expr == "" {
+		return nil, fmt.Errorf("empty regex expression")
+	}
+
+	// add the last $ if missing (and not wildcard(?))
+	if i := expr[len(expr)-1]; i != '$' && i != '*' {
+		expr += "$"
+	}
+
+	r, err := regexp.Compile(expr)
+	if err != nil {
+		return nil, err
+	}
+
+	return r.MatchString, nil
+}