Merge pull request #2095 from xushiwei/q

demo: gop-parser/gopcalc

cl/expr.go

@@ -1053,10 +1053,12 @@ func compileStringLitEx(ctx *blockCtx, cb *gogen.CodeBuilder, lit *ast.BasicLit)
 			t := cb.Get(-1).Type
 			if t.Underlying() != types.Typ[types.String] {
 				if _, err := cb.Member("string", gogen.MemberFlagAutoProperty); err != nil {
-					if e, ok := err.(*gogen.CodeError); ok {
-						err = ctx.newCodeErrorf(v.Pos(), "%s.string%s", ctx.LoadExpr(v), e.Msg)
+					if _, e2 := cb.Member("error", gogen.MemberFlagAutoProperty); e2 != nil {
+						if e, ok := err.(*gogen.CodeError); ok {
+							err = ctx.newCodeErrorf(v.Pos(), "%s.string%s", ctx.LoadExpr(v), e.Msg)
+						}
+						ctx.handleErr(err)
 					}
-					ctx.handleErr(err)
 				}
 			}
 			pos = v.End()

demo/gop-parser/gopcalc/calc.gop

@@ -0,0 +1,52 @@
+import (
+	"gop/ast"
+	"gop/parser"
+	"gop/token"
+	"math"
+	"os"
+)
+
+func calc(e ast.Expr) float64 {
+	switch e := e.(type) {
+	case *ast.BasicLit:
+		return e.Value.float!
+	case *ast.BinaryExpr:
+		switch e.Op {
+		case token.ADD:
+			return calc(e.X) + calc(e.Y)
+		case token.SUB:
+			return calc(e.X) - calc(e.Y)
+		case token.MUL:
+			return calc(e.X) * calc(e.Y)
+		case token.QUO:
+			return calc(e.X) + calc(e.Y)
+		}
+	case *ast.CallExpr:
+		switch e.Fun.(*ast.Ident).Name {
+		case "sin":
+			return math.Sin(calc(e.Args[0]))
+		case "cos":
+			return math.Cos(calc(e.Args[0]))
+		case "pow":
+			return math.Pow(calc(e.Args[0]), calc(e.Args[1]))
+		}
+	case *ast.ParenExpr:
+		return calc(e.X)
+	case *ast.UnaryExpr:
+		switch e.Op {
+		case token.SUB:
+			return -calc(e.X)
+		}
+	}
+	panic("unknown expression")
+}
+
+print "> "
+for line <- lines(os.Stdin) {
+	e, err := parser.parseExpr(line)
+	if err != nil {
+		print "error: ${err}\n> "
+	} else {
+		print "${calc(e)}\n> "
+	}
+}

demo/gop-parser/parser.gop

@@ -0,0 +1,7 @@
+import (
+	"gop/ast"
+	"gop/parser"
+)
+
+e := parser.parseExpr("10 + 3.2")!.(*ast.BinaryExpr)
+echo e.X, e.Op, e.Y