增加 noerr 函数

engine/def.go

@@ -29,6 +29,8 @@ var defFunC = map[string]int{
 	"sqrt":  1,
 	"cbrt":  1,
 
+	"noerr": 1,
+
 	"max": 2,
 	"min": 2,
 }
@@ -51,6 +53,8 @@ func init() {
 		"sqrt":  defSqrt,
 		"cbrt":  defCbrt,
 
+		"noerr": defNoerr,
+
 		"max": defMax,
 		"min": defMin,
 	}
@@ -130,3 +134,14 @@ func defMin(expr []ExprAST) float64 {
 func p2(expr []ExprAST) (float64, float64) {
 	return ExprASTResult(expr[0]), ExprASTResult(expr[1])
 }
+
+// noerr(1/0) = 0
+// noerr(2.5/(1-1)) = 0
+func defNoerr(expr []ExprAST) (r float64) {
+	defer func() {
+		if e := recover(); e != nil {
+			r = 0
+		}
+	}()
+	return ExprASTResult(expr[0])
+}

engine/util_test.go

@@ -58,6 +58,8 @@ func TestParseAndExecSimple(t *testing.T) {
 		{"min(2^3,3+abs(-1)*6)", 8},
 		{"max(2^3,3^2)", 9},
 		{"min(2^3,3^2)", 8},
+		{"noerr(1/0)", 0},
+		{"noerr(1/(1-1))", 0},
 	}
 	for _, e := range exprs {
 		r, _ := ParseAndExec(e.Expr)
@@ -118,6 +120,8 @@ func TestParseAndExecError(t *testing.T) {
 		"max(1,)",
 		"min(1,)",
 		"min(1,3, 099)",
+		"1/0",
+		"99.9 / (2-1-1)",
 	}
 	for _, e := range exprs {
 		_, err := ParseAndExec(e)

main_test.go

@@ -86,3 +86,13 @@ func TestExecQ(t *testing.T) {
 	exp := "2e-3*2+2e2+1"
 	exec(exp)
 }
+
+func TestExecR(t *testing.T) {
+	exp := "3.8 - 56 / (1-1) - 4"
+	exec(exp)
+}
+
+func TestExecS(t *testing.T) {
+	exp := "noerr(3.8 - 56 / (1-1) - 4)"
+	exec(exp)
+}