1 files changed, 52 insertions, 0 deletions
diff --git a/lexpr.go b/lexpr.go
new file mode 100644
index 0000000..fc3bbf8
--- /dev/null
+++ b/lexpr.go
@@ -0,0 +1,52 @@
+package lexpr
+
+import (
+	"context"
+	"strings"
+)
+
+type Lexpr struct {
+	operators map[string]Operator
+	functions map[string]func(ts *TokenStack) error
+	variables map[string]any
+}
+
+func New(opts ...Opt) *Lexpr {
+	l := &Lexpr{}
+	for _, o := range opts {
+		o(l)
+	}
+	return l
+}
+
+func (l *Lexpr) Eval(ctx context.Context, expression string) chan Result {
+	lexer := newLex()
+	lexems := lexer.parse(ctx, expression)
+	tokens := l.tokenize(ctx, lexems)
+	rpnTokens := infixToRpn(ctx, tokens)
+	return l.execute(ctx, rpnTokens)
+}
+
+func (l *Lexpr) SetFunction(name string, fn func(ts *TokenStack) error) *Lexpr {
+	l.functions[strings.ToLower(name)] = fn
+	return l
+}
+
+func (l *Lexpr) SetOperator(name string, fn func(ts *TokenStack) error, priority int, leftAssoc bool) *Lexpr {
+	l.operators[strings.ToLower(name)] = Operator{
+		handler:   fn,
+		priority:  priority,
+		leftAssoc: leftAssoc,
+	}
+	return l
+}
+
+func (l *Lexpr) SetVariable(name string, value any) *Lexpr {
+	l.variables[strings.ToLower(name)] = value
+	return l
+}
+
+type Result struct {
+	Value any
+	Error error
+}