wip

vendor/github.com/antonmedv/expr/conf/config.go

@@ -0,0 +1,89 @@
+package conf
+
+import (
+	"fmt"
+	"reflect"
+
+	"github.com/antonmedv/expr/ast"
+	"github.com/antonmedv/expr/vm"
+)
+
+type Config struct {
+	Env          interface{}
+	MapEnv       bool
+	Types        TypesTable
+	Operators    OperatorsTable
+	Expect       reflect.Kind
+	Optimize     bool
+	Strict       bool
+	DefaultType  reflect.Type
+	ConstExprFns map[string]reflect.Value
+	Visitors     []ast.Visitor
+	err          error
+}
+
+func New(env interface{}) *Config {
+	var mapEnv bool
+	var mapValueType reflect.Type
+	if _, ok := env.(map[string]interface{}); ok {
+		mapEnv = true
+	} else {
+		if reflect.ValueOf(env).Kind() == reflect.Map {
+			mapValueType = reflect.TypeOf(env).Elem()
+		}
+	}
+
+	return &Config{
+		Env:          env,
+		MapEnv:       mapEnv,
+		Types:        CreateTypesTable(env),
+		Optimize:     true,
+		Strict:       true,
+		DefaultType:  mapValueType,
+		ConstExprFns: make(map[string]reflect.Value),
+	}
+}
+
+// Check validates the compiler configuration.
+func (c *Config) Check() error {
+	// Check that all functions that define operator overloading
+	// exist in environment and have correct signatures.
+	for op, fns := range c.Operators {
+		for _, fn := range fns {
+			fnType, ok := c.Types[fn]
+			if !ok || fnType.Type.Kind() != reflect.Func {
+				return fmt.Errorf("function %s for %s operator does not exist in environment", fn, op)
+			}
+			requiredNumIn := 2
+			if fnType.Method {
+				requiredNumIn = 3 // As first argument of method is receiver.
+			}
+			if fnType.Type.NumIn() != requiredNumIn || fnType.Type.NumOut() != 1 {
+				return fmt.Errorf("function %s for %s operator does not have a correct signature", fn, op)
+			}
+		}
+	}
+
+	// Check that all ConstExprFns are functions.
+	for name, fn := range c.ConstExprFns {
+		if fn.Kind() != reflect.Func {
+			return fmt.Errorf("const expression %q must be a function", name)
+		}
+	}
+
+	return c.err
+}
+
+func (c *Config) ConstExpr(name string) {
+	if c.Env == nil {
+		c.Error(fmt.Errorf("no environment for const expression: %v", name))
+		return
+	}
+	c.ConstExprFns[name] = vm.FetchFn(c.Env, name)
+}
+
+func (c *Config) Error(err error) {
+	if c.err == nil {
+		c.err = err
+	}
+}