context.go splitted in two files: expr-context.go and expr-function-go.

Expr interface moved from ast.go to the new file expr.go

expr-function.go

@@ -0,0 +1,37 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// context.go
+package expr
+
+// ---- Functor interface
+type Functor interface {
+	Invoke(ctx ExprContext, name string, args []any) (result any, err error)
+	SetFunc(info ExprFunc)
+	GetFunc() ExprFunc
+	GetParams() []ExprFuncParam
+	GetDefinitionContext() ExprContext
+}
+
+// ---- Function Param Info
+type ExprFuncParam interface {
+	Name() string
+	Type() string
+	IsDefault() bool
+	IsOptional() bool
+	IsRepeat() bool
+	DefaultValue() any
+}
+
+// ---- Function Info
+type ExprFunc interface {
+	Formatter
+	Name() string
+	MinArgs() int
+	MaxArgs() int
+	Functor() Functor
+	Params() []ExprFuncParam
+	ReturnType() string
+	PrepareCall(parentCtx ExprContext, name string, varParams *[]any) (ctx ExprContext, err error)
+	AllocContext(parentCtx ExprContext) (ctx ExprContext)
+}