Add support for limited mode without unsafe pkg.

This commit adds support for compiling spew without the unsafe package.
When compiled without the unsafe package, some of the more advanced
features such as invoking stringers on pointers from non-pointer
variables and unexported struct fields are not available.

By default, spew will be compiled in the limited mode for Google App
Engine since the unsafe package is not available there.  Additionally,
spew can be compiled without the unsafe package manually by specifying
the "disableunsafe" build tag.

Finally, a new package-level constant named "UnsafeDisabled" has been
exposed which can be used to programmatically determine if spew was
compiled with access to the unsafe package.

1 files changed, 53 insertions, 32 deletions

diff --git a/spew/dump_test.go b/spew/dump_test.go
index 3dd9089..2b32040 100644
--- a/spew/dump_test.go
+++ b/spew/dump_test.go
@@ -334,13 +334,20 @@ func addArrayDumpTests() {
 	v2Addr := fmt.Sprintf("%p", pv2)
 	pv2Addr := fmt.Sprintf("%p", &pv2)
 	v2t := "spew_test.pstringer"
-	v2s := "(len=" + v2Len + " cap=" + v2Cap + ") {\n (" + v2t + ") (len=" +
-		v2i0Len + ") stringer 1,\n (" + v2t + ") (len=" + v2i1Len +
-		") stringer 2,\n (" + v2t + ") (len=" + v2i2Len + ") " +
-		"stringer 3\n}"
+	v2sp := "(len=" + v2Len + " cap=" + v2Cap + ") {\n (" + v2t +
+		") (len=" + v2i0Len + ") stringer 1,\n (" + v2t +
+		") (len=" + v2i1Len + ") stringer 2,\n (" + v2t +
+		") (len=" + v2i2Len + ") " + "stringer 3\n}"
+	v2s := v2sp
+	if spew.UnsafeDisabled {
+		v2s = "(len=" + v2Len + " cap=" + v2Cap + ") {\n (" + v2t +
+			") (len=" + v2i0Len + ") \"1\",\n (" + v2t + ") (len=" +
+			v2i1Len + ") \"2\",\n (" + v2t + ") (len=" + v2i2Len +
+			") " + "\"3\"\n}"
+	}
 	addDumpTest(v2, "([3]"+v2t+") "+v2s+"\n")
-	addDumpTest(pv2, "(*[3]"+v2t+")("+v2Addr+")("+v2s+")\n")
-	addDumpTest(&pv2, "(**[3]"+v2t+")("+pv2Addr+"->"+v2Addr+")("+v2s+")\n")
+	addDumpTest(pv2, "(*[3]"+v2t+")("+v2Addr+")("+v2sp+")\n")
+	addDumpTest(&pv2, "(**[3]"+v2t+")("+pv2Addr+"->"+v2Addr+")("+v2sp+")\n")
 	addDumpTest(nv2, "(*[3]"+v2t+")(<nil>)\n")
 
 	// Array containing interfaces.
@@ -587,6 +594,11 @@ func addMapDumpTests() {
 	m2t2 := "spew_test.pstringer"
 	m2s := "(len=" + m2Len + ") {\n (" + m2t1 + ") (len=" + k2Len + ") " +
 		"stringer one: (" + m2t2 + ") (len=" + v2Len + ") stringer 1\n}"
+	if spew.UnsafeDisabled {
+		m2s = "(len=" + m2Len + ") {\n (" + m2t1 + ") (len=" + k2Len +
+			") " + "\"one\": (" + m2t2 + ") (len=" + v2Len +
+			") \"1\"\n}"
+	}
 	addDumpTest(m2, "("+m2t+") "+m2s+"\n")
 	addDumpTest(pm2, "(*"+m2t+")("+m2Addr+")("+m2s+")\n")
 	addDumpTest(&pm2, "(**"+m2t+")("+pm2Addr+"->"+m2Addr+")("+m2s+")\n")
@@ -693,9 +705,16 @@ func addStructDumpTests() {
 	v3t2 := "spew_test.pstringer"
 	v3s := "{\n s: (" + v3t2 + ") (len=4) stringer test,\n S: (" + v3t2 +
 		") (len=5) stringer test2\n}"
+	v3sp := v3s
+	if spew.UnsafeDisabled {
+		v3s = "{\n s: (" + v3t2 + ") (len=4) \"test\",\n S: (" +
+			v3t2 + ") (len=5) \"test2\"\n}"
+		v3sp = "{\n s: (" + v3t2 + ") (len=4) \"test\",\n S: (" +
+			v3t2 + ") (len=5) stringer test2\n}"
+	}
 	addDumpTest(v3, "("+v3t+") "+v3s+"\n")
-	addDumpTest(pv3, "(*"+v3t+")("+v3Addr+")("+v3s+")\n")
-	addDumpTest(&pv3, "(**"+v3t+")("+pv3Addr+"->"+v3Addr+")("+v3s+")\n")
+	addDumpTest(pv3, "(*"+v3t+")("+v3Addr+")("+v3sp+")\n")
+	addDumpTest(&pv3, "(**"+v3t+")("+pv3Addr+"->"+v3Addr+")("+v3sp+")\n")
 	addDumpTest(nv3, "(*"+v3t+")(<nil>)\n")
 
 	// Struct that contains embedded struct and field to same struct.
@@ -975,45 +994,47 @@ func TestDump(t *testing.T) {
 func TestDumpSortedKeys(t *testing.T) {
 	cfg := spew.ConfigState{SortKeys: true}
 	s := cfg.Sdump(map[int]string{1: "1", 3: "3", 2: "2"})
-	expected := `(map[int]string) (len=3) {
-(int) 1: (string) (len=1) "1",
-(int) 2: (string) (len=1) "2",
-(int) 3: (string) (len=1) "3"
-}
-`
+	expected := "(map[int]string) (len=3) {\n(int) 1: (string) (len=1) " +
+		"\"1\",\n(int) 2: (string) (len=1) \"2\",\n(int) 3: (string) " +
+		"(len=1) \"3\"\n" +
+		"}\n"
 	if s != expected {
 		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
 	}
 
 	s = cfg.Sdump(map[stringer]int{"1": 1, "3": 3, "2": 2})
-	expected = `(map[spew_test.stringer]int) (len=3) {
-(spew_test.stringer) (len=1) stringer 1: (int) 1,
-(spew_test.stringer) (len=1) stringer 2: (int) 2,
-(spew_test.stringer) (len=1) stringer 3: (int) 3
-}
-`
+	expected = "(map[spew_test.stringer]int) (len=3) {\n" +
+		"(spew_test.stringer) (len=1) stringer 1: (int) 1,\n" +
+		"(spew_test.stringer) (len=1) stringer 2: (int) 2,\n" +
+		"(spew_test.stringer) (len=1) stringer 3: (int) 3\n" +
+		"}\n"
 	if s != expected {
 		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
 	}
 
 	s = cfg.Sdump(map[pstringer]int{pstringer("1"): 1, pstringer("3"): 3, pstringer("2"): 2})
-	expected = `(map[spew_test.pstringer]int) (len=3) {
-(spew_test.pstringer) (len=1) stringer 1: (int) 1,
-(spew_test.pstringer) (len=1) stringer 2: (int) 2,
-(spew_test.pstringer) (len=1) stringer 3: (int) 3
-}
-`
+	expected = "(map[spew_test.pstringer]int) (len=3) {\n" +
+		"(spew_test.pstringer) (len=1) stringer 1: (int) 1,\n" +
+		"(spew_test.pstringer) (len=1) stringer 2: (int) 2,\n" +
+		"(spew_test.pstringer) (len=1) stringer 3: (int) 3\n" +
+		"}\n"
+	if spew.UnsafeDisabled {
+		expected = "(map[spew_test.pstringer]int) (len=3) {\n" +
+			"(spew_test.pstringer) (len=1) \"1\": (int) 1,\n" +
+			"(spew_test.pstringer) (len=1) \"2\": (int) 2,\n" +
+			"(spew_test.pstringer) (len=1) \"3\": (int) 3\n" +
+			"}\n"
+	}
 	if s != expected {
 		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
 	}
 
 	s = cfg.Sdump(map[customError]int{customError(1): 1, customError(3): 3, customError(2): 2})
-	expected = `(map[spew_test.customError]int) (len=3) {
-(spew_test.customError) error: 1: (int) 1,
-(spew_test.customError) error: 2: (int) 2,
-(spew_test.customError) error: 3: (int) 3
-}
-`
+	expected = "(map[spew_test.customError]int) (len=3) {\n" +
+		"(spew_test.customError) error: 1: (int) 1,\n" +
+		"(spew_test.customError) error: 2: (int) 2,\n" +
+		"(spew_test.customError) error: 3: (int) 3\n" +
+		"}\n"
 	if s != expected {
 		t.Errorf("Sorted keys mismatch:\n  %v %v", s, expected)
 	}