refactor: unify Func,Macro interfaces to Op interface

Author: tyru

dsl/deparse.go

@@ -41,8 +41,8 @@ func deparse(value types.Value) (interface{}, error) {
 	case *types.Expr:
 		a := make([]interface{}, 0, len(val.Args())+1)
 		// Do not include "@" in array literal
-		if val.Func().String() != op.ArrayOp.String() {
-			a = append(a, types.NewString(val.Func().String()))
+		if val.Op().String() != op.ArrayOp.String() {
+			a = append(a, types.NewString(val.Op().String()))
 		}
 		for i := range a {
 			v, err := deparse(val.Args()[i])

dsl/op/array.go

@@ -1,26 +1,31 @@
 package op
 
 import (
+	"context"
+
 	"github.com/vim-volt/volt/dsl/types"
 )
 
 func init() {
-	s := arrayOp("$array")
-	ArrayOp = &s
-	macroMap[string(*ArrayOp)] = ArrayOp
+	opsMap[ArrayOp.String()] = ArrayOp
+}
+
+type arrayOp struct {
+	macroBase
 }
 
-type arrayOp string
+// ArrayOp is "$array" operator
+var ArrayOp = &arrayOp{macroBase("$array")}
 
-// ArrayOp is "$array" operation
-var ArrayOp *arrayOp
+func (op *arrayOp) InvertExpr(args []types.Value) (types.Value, error) {
+	return op.macroInvertExpr(op.Execute(context.Background(), args))
+}
 
-// String returns "$array"
-func (*arrayOp) String() string {
-	return string(*ArrayOp)
+func (*arrayOp) Bind(args ...types.Value) (*types.Expr, error) {
+	expr := types.NewExpr(ArrayOp, args, types.NewArrayType(types.AnyValue))
+	return expr, nil
 }
 
-// Execute executes "$array" operation
-func (*arrayOp) Expand(args []types.Value) (types.Value, func(), error) {
+func (*arrayOp) Execute(ctx context.Context, args []types.Value) (types.Value, func(), error) {
 	return types.NewArray(args, types.AnyValue), NoRollback, nil
 }

dsl/op/do.go

@@ -9,20 +9,22 @@ import (
 func init() {
 	opName := doOp("do")
 	DoOp = &opName
-	funcMap["do"] = DoOp
+	opsMap["do"] = DoOp
 }
 
 type doOp string
 
 // DoOp is "do" operation
 var DoOp *doOp
 
-// String returns operator name
 func (*doOp) String() string {
 	return string(*DoOp)
 }
 
-// Bind binds its arguments, and check if the types of values are correct.
+func (*doOp) IsMacro() bool {
+	return false
+}
+
 func (*doOp) Bind(args ...types.Value) (*types.Expr, error) {
 	sig := make([]types.Type, 0, len(args))
 	for i := 0; i < len(args); i++ {
@@ -35,9 +37,7 @@ func (*doOp) Bind(args ...types.Value) (*types.Expr, error) {
 	return types.NewExpr(DoOp, args, retType), nil
 }
 
-// InvertExpr returns inverted expression: Call Value.Invert() for each argument,
-// and reverse arguments order.
-func (*doOp) InvertExpr(args []types.Value) (*types.Expr, error) {
+func (*doOp) InvertExpr(args []types.Value) (types.Value, error) {
 	newargs := make([]types.Value, len(args))
 	for i := range args {
 		a, err := args[i].Invert()
@@ -49,7 +49,6 @@ func (*doOp) InvertExpr(args []types.Value) (*types.Expr, error) {
 	return DoOp.Bind(newargs...)
 }
 
-// Execute executes "do" operation
 func (*doOp) Execute(ctx context.Context, args []types.Value) (val types.Value, rollback func(), err error) {
 	g := funcGuard(DoOp.String())
 	defer func() { err = g.rollback(recover()) }()

dsl/op/eval.go

@@ -7,23 +7,26 @@ import (
 )
 
 func init() {
-	s := evalOp("$eval")
-	EvalOp = &s
-	macroMap[string(*EvalOp)] = EvalOp
+	opsMap[EvalOp.String()] = EvalOp
 }
 
-type evalOp string
+type evalOp struct {
+	macroBase
+}
+
+// EvalOp is "$eval" operator
+var EvalOp = &evalOp{macroBase("$eval")}
 
-// EvalOp is "$eval" operation
-var EvalOp *evalOp
+func (op *evalOp) InvertExpr(args []types.Value) (types.Value, error) {
+	return op.macroInvertExpr(op.Execute(context.Background(), args))
+}
 
-// String returns "$eval"
-func (*evalOp) String() string {
-	return string(*EvalOp)
+func (*evalOp) Bind(args ...types.Value) (*types.Expr, error) {
+	expr := types.NewExpr(ArrayOp, args, types.NewArrayType(types.AnyValue))
+	return expr, nil
 }
 
-// Execute executes "$eval" operation
-func (*evalOp) Expand(args []types.Value) (types.Value, func(), error) {
+func (*evalOp) Execute(ctx context.Context, args []types.Value) (types.Value, func(), error) {
 	if err := signature(types.AnyValue).check(args); err != nil {
 		return nil, NoRollback, err
 	}

dsl/op/invert.go

@@ -1,27 +1,32 @@
 package op
 
 import (
+	"context"
+
 	"github.com/vim-volt/volt/dsl/types"
 )
 
 func init() {
-	s := invertOp("$invert")
-	InvertOp = &s
-	macroMap[string(*InvertOp)] = InvertOp
+	opsMap[InvertOp.String()] = InvertOp
+}
+
+type invertOp struct {
+	macroBase
 }
 
-type invertOp string
+// InvertOp is "$invert" operator
+var InvertOp = &invertOp{macroBase("$invert")}
 
-// InvertOp is "$invert" operation
-var InvertOp *invertOp
+func (op *invertOp) InvertExpr(args []types.Value) (types.Value, error) {
+	return op.macroInvertExpr(op.Execute(context.Background(), args))
+}
 
-// String returns "$invert"
-func (*invertOp) String() string {
-	return string(*InvertOp)
+func (*invertOp) Bind(args ...types.Value) (*types.Expr, error) {
+	expr := types.NewExpr(ArrayOp, args, types.NewArrayType(types.AnyValue))
+	return expr, nil
 }
 
-// Execute executes "$invert" operation
-func (*invertOp) Expand(args []types.Value) (types.Value, func(), error) {
+func (*invertOp) Execute(ctx context.Context, args []types.Value) (types.Value, func(), error) {
 	if err := signature(types.AnyValue).check(args); err != nil {
 		return nil, NoRollback, err
 	}

dsl/op/lookup.go

@@ -2,22 +2,12 @@ package op
 
 import "github.com/vim-volt/volt/dsl/types"
 
-// funcMap holds all operation structs.
+// opsMap holds all operation structs.
 // All operations in dsl/op/*.go sets its struct to this in init()
-var funcMap map[string]types.Func
+var opsMap map[string]types.Op
 
-// LookupFunc looks up function name
-func LookupFunc(name string) (types.Func, bool) {
-	op, exists := funcMap[name]
-	return op, exists
-}
-
-// macroMap holds all operation structs.
-// All operations in dsl/op/*.go sets its struct to this in init()
-var macroMap map[string]types.Macro
-
-// LookupMacro looks up macro name
-func LookupMacro(name string) (types.Macro, bool) {
-	op, exists := macroMap[name]
+// Lookup looks up operator name
+func Lookup(name string) (types.Op, bool) {
+	op, exists := opsMap[name]
 	return op, exists
 }

dsl/op/macro.go

@@ -0,0 +1,24 @@
+package op
+
+import (
+	"github.com/vim-volt/volt/dsl/types"
+)
+
+type macroBase string
+
+// String returns "$array"
+func (m *macroBase) String() string {
+	return string(*m)
+}
+
+func (*macroBase) IsMacro() bool {
+	return true
+}
+
+// Invert the result of op.Execute() which expands an expression
+func (*macroBase) macroInvertExpr(val types.Value, _ func(), err error) (types.Value, error) {
+	if err != nil {
+		return nil, err
+	}
+	return val.Invert()
+}

dsl/parse.go

@@ -1,6 +1,7 @@
 package dsl
 
 import (
+	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
@@ -51,14 +52,16 @@ func parseArray(array []interface{}) (types.Value, error) {
 		}
 		args = append(args, v)
 	}
-	if macro, exists := op.LookupMacro(opName); exists {
-		val, _, err := macro.Expand(args)
-		return val, err
+	op, exists := op.Lookup(opName)
+	if !exists {
+		return nil, fmt.Errorf("no such operation '%s'", opName)
 	}
-	if fn, exists := op.LookupFunc(opName); exists {
-		return fn.Bind(args...)
+	// Expand macro's expression at parsing time
+	if op.IsMacro() {
+		val, _, err := op.Execute(context.Background(), args)
+		return val, err
 	}
-	return nil, fmt.Errorf("no such operation '%s'", opName)
+	return op.Bind(args...)
 }
 
 func parse(value interface{}) (types.Value, error) {

dsl/types/expr.go

@@ -4,14 +4,14 @@ import "context"
 
 // Expr has an operation and its arguments
 type Expr struct {
-	fun     Func
+	op      Op
 	args    []Value
 	retType Type
 }
 
-// Func returns function of Expr
-func (expr *Expr) Func() Func {
-	return expr.fun
+// Op returns operator of Expr
+func (expr *Expr) Op() Op {
+	return expr.op
 }
 
 // Args returns arguments of Expr
@@ -25,19 +25,19 @@ func (expr *Expr) RetType() Type {
 }
 
 // NewExpr creates Expr instance
-func NewExpr(fun Func, args []Value, retType Type) *Expr {
-	return &Expr{fun: fun, args: args, retType: retType}
+func NewExpr(op Op, args []Value, retType Type) *Expr {
+	return &Expr{op: op, args: args, retType: retType}
 }
 
 // Eval evaluates given expression expr with given transaction ID trxID.
 func (expr *Expr) Eval(ctx context.Context) (val Value, rollback func(), err error) {
-	return expr.fun.Execute(ctx, expr.args)
+	return expr.op.Execute(ctx, expr.args)
 }
 
 // Invert inverts this expression.
-// This just calls Func.InvertExpr() with arguments.
+// This just calls Op().InvertExpr() with saved arguments.
 func (expr *Expr) Invert() (Value, error) {
-	return expr.fun.InvertExpr(expr.args)
+	return expr.op.InvertExpr(expr.args)
 }
 
 // Type returns the type.

dsl/types/op.go

@@ -2,27 +2,20 @@ package types
 
 import "context"
 
-// Func is an operation of JSON DSL
-type Func interface {
+// Op is an operation of JSON DSL
+type Op interface {
 	// String returns function name
 	String() string
 
 	// InvertExpr returns inverted expression
-	InvertExpr(args []Value) (*Expr, error)
+	InvertExpr(args []Value) (Value, error)
 
-	// Bind binds its arguments, and check if the types of values are correct.
+	// Bind binds its arguments, and check if the types of values are correct
 	Bind(args ...Value) (*Expr, error)
 
 	// Execute executes this operation and returns its result value and error
 	Execute(ctx context.Context, args []Value) (ret Value, rollback func(), err error)
-}
-
-// Macro is an operation of JSON DSL
-type Macro interface {
-	// String returns macro name
-	String() string
 
-	// Expand expands this expression (operator + args).
-	// If argument type or arity is different, this returns non-nil error.
-	Expand(args []Value) (val Value, rollback func(), err error)
+	// IsMacro returns true if this operator is a macro
+	IsMacro() bool
 }