Add std.round function in standard library.

Author: rohitjangid

builtins.go

@@ -1072,6 +1072,7 @@ var builtinExponent = liftNumeric(func(f float64) float64 {
 	_, exponent := math.Frexp(f)
 	return float64(exponent)
 })
+var builtinRound = liftNumeric(math.Round)
 
 func liftBitwise(f func(int64, int64) int64, positiveRightArg bool) func(*interpreter, value, value) (value, error) {
 	return func(i *interpreter, xv, yv value) (value, error) {
@@ -2195,6 +2196,7 @@ var funcBuiltins = buildBuiltinMap([]builtin{
 	&unaryBuiltin{name: "exp", function: builtinExp, params: ast.Identifiers{"x"}},
 	&unaryBuiltin{name: "mantissa", function: builtinMantissa, params: ast.Identifiers{"x"}},
 	&unaryBuiltin{name: "exponent", function: builtinExponent, params: ast.Identifiers{"x"}},
+	&unaryBuiltin{name: "round", function: builtinRound, params: ast.Identifiers{"x"}},
 	&binaryBuiltin{name: "pow", function: builtinPow, params: ast.Identifiers{"x", "n"}},
 	&binaryBuiltin{name: "modulo", function: builtinModulo, params: ast.Identifiers{"x", "y"}},
 	&unaryBuiltin{name: "md5", function: builtinMd5, params: ast.Identifiers{"s"}},

linter/internal/types/stdlib.go

@@ -65,6 +65,7 @@ func prepareStdlib(g *typeGraph) {
 		"asin":     g.newSimpleFuncType(numberType, "x"),
 		"acos":     g.newSimpleFuncType(numberType, "x"),
 		"atan":     g.newSimpleFuncType(numberType, "x"),
+		"round":    g.newSimpleFuncType(numberType, "x"),
 
 		// Assertions and debugging
 		"assertEqual": g.newSimpleFuncType(boolType, "a", "b"),
@@ -174,7 +175,7 @@ func prepareStdlib(g *typeGraph) {
 
 		// Boolean
 
-		"xor":	g.newSimpleFuncType(boolType, "x", "y"),
+		"xor": g.newSimpleFuncType(boolType, "x", "y"),
 	}
 
 	fieldContains := map[string][]placeholderID{}

testdata/builtinRound.golden

@@ -0,0 +1 @@
+2

testdata/builtinRound.jsonnet

@@ -0,0 +1 @@
+std.round(2.3)