pkg/net: added package

Support:
- various IP types
- FQDNs

Also supports:
- use of single-param builtins as types
  (consistent with curried builtins).
- fixed bug in interpretation of top
- allow unexported functions to be used by builtins

Change-Id: I3568f2383510a904e00d4cf941c753efd03679ce
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2664
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: mpvl

cue/binop.go

@@ -53,6 +53,9 @@ func binOp(ctx *context, src source, op op, left, right evaluated) (result evalu
 		return right
 	}
 
+	left = convertBuiltin(left)
+	right = convertBuiltin(right)
+
 	leftKind := left.kind()
 	rightKind := right.kind()
 	kind, invert, msg := matchBinOpKind(op, leftKind, rightKind)
@@ -125,7 +128,7 @@ func binOp(ctx *context, src source, op op, left, right evaluated) (result evalu
 		v := right.binOp(ctx, src, op, left)
 		// Return the original failure if both fail, as this will result in
 		// better error messages.
-		if !isBottom(v) {
+		if !isBottom(v) || isCustom(v) {
 			return v
 		}
 	}

cue/builtin.go

@@ -195,6 +195,14 @@ func (x *builtin) name(ctx *context) string {
 	return fmt.Sprintf("%s.%s", ctx.labelStr(x.pkg), x.Name)
 }
 
+func convertBuiltin(v evaluated) evaluated {
+	x, ok := v.(*builtin)
+	if ok && len(x.Params) == 1 && x.Result == boolKind {
+		return &customValidator{v.base(), []evaluated{}, x}
+	}
+	return v
+}
+
 func (x *builtin) call(ctx *context, src source, args ...evaluated) (ret value) {
 	if x.Func == nil {
 		return ctx.mkErr(x, "builtin %s is not a function", x.name(ctx))

cue/builtin_test.go

@@ -185,6 +185,57 @@ func TestBuiltins(t *testing.T) {
 	}, {
 		test("encoding/yaml", `yaml.MarshalStream([{a: 1}, {b: 2}])`),
 		`"a: 1\n---\nb: 2\n"`,
+	}, {
+		test("net", `net.FQDN & "foo.bar."`),
+		`"foo.bar."`,
+	}, {
+		test("net", `net.FQDN("foo.bararararararararararararararararararararararararararararararararara")`),
+		`false`,
+	}, {
+		test("net", `net.SplitHostPort("[::%lo0]:80")`),
+		`["::%lo0","80"]`,
+	}, {
+		test("net", `net.JoinHostPort("example.com", "80")`),
+		`"example.com:80"`,
+	}, {
+		test("net", `net.JoinHostPort("2001:db8::1", 80)`),
+		`"[2001:db8::1]:80"`,
+	}, {
+		test("net", `net.JoinHostPort([192,30,4,2], 80)`),
+		`"192.30.4.2:80"`,
+	}, {
+		test("net", `net.JoinHostPort([192,30,4], 80)`),
+		`_|_(error in call to net.JoinHostPort: invalid host [192,30,4])`,
+	}, {
+		test("net", `net.IP("23.23.23.23")`),
+		`true`,
+	}, {
+		test("net", `net.IPv4 & "23.23.23.2333"`),
+		`_|_(invalid value "23.23.23.2333" (does not satisfy net.IPv4()))`,
+	}, {
+		test("net", `net.IP("23.23.23.23")`),
+		`true`,
+	}, {
+		test("net", `net.IP("2001:db8::1")`),
+		`true`,
+	}, {
+		test("net", `net.IPv4("2001:db8::1")`),
+		`false`,
+	}, {
+		test("net", `net.IPv4() & "ff02::1:3"`),
+		`_|_(invalid value "ff02::1:3" (does not satisfy net.IPv4()))`,
+	}, {
+		test("net", `net.LoopbackIP([127, 0, 0, 1])`),
+		`true`,
+	}, {
+		test("net", `net.LoopbackIP("127.0.0.1")`),
+		`true`,
+	}, {
+		test("net", `net.ToIP4("127.0.0.1")`),
+		`[127,0,0,1]`,
+	}, {
+		test("net", `net.ToIP16("127.0.0.1")`),
+		`[0,0,0,0,0,0,0,0,0,0,255,255,127,0,0,1]`,
 	}, {
 		test("strings", `strings.ToCamel("AlphaBeta")`),
 		`"alphaBeta"`,