exp/template: handle pointers and values in empty interfaces.

R=golang-dev, r, mattn.jp
CC=golang-dev
https://golang.org/cl/4664064

diff --git a/src/pkg/exp/template/exec.go b/src/pkg/exp/template/exec.go
index 6f171da3847c652ad6f801cbb511823223dd3774..fb0a9e62186ff3d183712a25ffb9c5fedb8eb2b1 100644 (file)
--- a/src/pkg/exp/template/exec.go
+++ b/src/pkg/exp/template/exec.go
@@ -245,8 +245,9 @@ func isExported(name string) bool {
 }
 
 func (s *state) evalField(data reflect.Value, fieldName string) reflect.Value {
-       for data.Kind() == reflect.Ptr {
-               data = reflect.Indirect(data)
+       var isNil bool
+       if data, isNil = indirect(data); isNil {
+               s.errorf("%s is nil pointer", fieldName)
        }
        switch data.Kind() {
        case reflect.Struct:
@@ -270,7 +271,7 @@ func (s *state) evalFieldOrCall(data reflect.Value, fieldName string, args []nod
                return s.evalCall(data, function, fieldName, false, args, final)
        }
        ptr := data
-       for data.Kind() == reflect.Ptr {
+       for data.Kind() == reflect.Ptr && !data.IsNil() {
                ptr, data = data, reflect.Indirect(data)
        }
        // Is it a method? We use the pointer because it has value methods too.
@@ -475,16 +476,30 @@ func (s *state) evalEmptyInterface(data reflect.Value, typ reflect.Type, n node)
        panic("not reached")
 }
 
+// indirect returns the item at the end of indirection, and a bool to indicate if it's nil.
+func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
+       for v.Kind() == reflect.Ptr {
+               if v.IsNil() {
+                       return v, true
+               }
+               v = v.Elem()
+       }
+       return v, false
+}
+
 // printValue writes the textual representation of the value to the output of
 // the template.
 func (s *state) printValue(n node, v reflect.Value) {
        if !v.IsValid() {
+               fmt.Fprint(s.wr, "<no value>")
                return
        }
        switch v.Kind() {
        case reflect.Ptr:
-               if v.IsNil() {
-                       s.errorf("%s: nil value", n)
+               var isNil bool
+               if v, isNil = indirect(v); isNil {
+                       fmt.Fprint(s.wr, "<nil>")
+                       return
                }
        case reflect.Chan, reflect.Func, reflect.Interface:
                s.errorf("can't print %s of type %s", n, v.Type())

diff --git a/src/pkg/exp/template/exec_test.go b/src/pkg/exp/template/exec_test.go
index f974673d44ced36bd52883df122dfded41381abb..8992299ebf018e8c5ee296810502c26551934167 100644 (file)
--- a/src/pkg/exp/template/exec_test.go
+++ b/src/pkg/exp/template/exec_test.go
@@ -32,8 +32,51 @@ type T struct {
        MSIone   map[string]int // one element, for deterministic output
        MSIEmpty map[string]int
        SMSI     []map[string]int
-       // Empty interface; used to see if we can dig inside one.
-       EmptyInterface interface{}
+       // Empty interfaces; used to see if we can dig inside one.
+       Empty0 interface{} // nil
+       Empty1 interface{}
+       Empty2 interface{}
+       Empty3 interface{}
+       Empty4 interface{}
+       // Pointers
+       PI  *int
+       PSI *[]int
+       NIL *int
+}
+
+var tVal = &T{
+       I:      17,
+       U16:    16,
+       X:      "x",
+       U:      &U{"v"},
+       SI:     []int{3, 4, 5},
+       SB:     []bool{true, false},
+       MSI:    map[string]int{"one": 1, "two": 2, "three": 3},
+       MSIone: map[string]int{"one": 1},
+       SMSI: []map[string]int{
+               {"one": 1, "two": 2},
+               {"eleven": 11, "twelve": 12},
+       },
+       Empty1: 3,
+       Empty2: "empty2",
+       Empty3: []int{7, 8},
+       Empty4: &U{"v"},
+       PI:     newInt(23),
+       PSI:    newIntSlice(21, 22, 23),
+}
+
+// Helpers for creation.
+func newInt(n int) *int {
+       p := new(int)
+       *p = n
+       return p
+}
+
+func newIntSlice(n ...int) *[]int {
+       p := new([]int)
+       *p = make([]int, len(n))
+       copy(*p, n)
+       return p
 }
 
 // Simple methods with and without arguments.
@@ -81,22 +124,6 @@ type U struct {
        V string
 }
 
-var tVal = &T{
-       I:      17,
-       U16:    16,
-       X:      "x",
-       U:      &U{"v"},
-       SI:     []int{3, 4, 5},
-       SB:     []bool{true, false},
-       MSI:    map[string]int{"one": 1, "two": 2, "three": 3},
-       MSIone: map[string]int{"one": 1},
-       SMSI: []map[string]int{
-               {"one": 1, "two": 2},
-               {"eleven": 11, "twelve": 12},
-       },
-       EmptyInterface: []int{7, 8},
-}
-
 type execTest struct {
        name   string
        input  string
@@ -109,9 +136,11 @@ var execTests = []execTest{
        // Trivial cases.
        {"empty", "", "", nil, true},
        {"text", "some text", "some text", nil, true},
+
        // Fields of structs.
        {".X", "-{{.X}}-", "-x-", tVal, true},
        {".U.V", "-{{.U.V}}-", "-v-", tVal, true},
+
        // Dots of all kinds to test basic evaluation.
        {"dot int", "<{{.}}>", "<13>", 13, true},
        {"dot uint", "<{{.}}>", "<14>", uint(14), true},
@@ -125,14 +154,30 @@ var execTests = []execTest{
                a int
                b string
        }{7, "seven"}, true},
+
+       // Pointers.
+       {"*int", "{{.PI}}", "23", tVal, true},
+       {"*[]int", "{{.PSI}}", "[21 22 23]", tVal, true},
+       {"*[]int[1]", "{{index .PSI 1}}", "22", tVal, true},
+       {"NIL", "{{.NIL}}", "<nil>", tVal, true},
+
+       // Emtpy interfaces holding values.
+       {"empty nil", "{{.Empty0}}", "<no value>", tVal, true},
+       {"empty with int", "{{.Empty1}}", "3", tVal, true},
+       {"empty with string", "{{.Empty2}}", "empty2", tVal, true},
+       {"empty with slice", "{{.Empty3}}", "[7 8]", tVal, true},
+       {"empty with struct", "{{.Empty4}}", "{v}", tVal, true},
+
        // Method calls.
        {".Method0", "-{{.Method0}}-", "-resultOfMethod0-", tVal, true},
        {".Method1(1234)", "-{{.Method1 1234}}-", "-1234-", tVal, true},
        {".Method1(.I)", "-{{.Method1 .I}}-", "-17-", tVal, true},
        {".Method2(3, .X)", "-{{.Method2 3 .X}}-", "-Method2: 3 x-", tVal, true},
        {".Method2(.U16, `str`)", "-{{.Method2 .U16 `str`}}-", "-Method2: 16 str-", tVal, true},
+
        // Pipelines.
        {"pipeline", "-{{.Method0 | .Method2 .U16}}-", "-Method2: 16 resultOfMethod0-", tVal, true},
+
        // If.
        {"if true", "{{if true}}TRUE{{end}}", "TRUE", tVal, true},
        {"if false", "{{if false}}TRUE{{else}}FALSE{{end}}", "FALSE", tVal, true},
@@ -148,6 +193,7 @@ var execTests = []execTest{
        {"if slice", "{{if .SI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
        {"if emptymap", "{{if .MSIEmpty}}NON-EMPTY{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
        {"if map", "{{if .MSI}}NON-EMPTY{{else}}EMPTY{{end}}", "NON-EMPTY", tVal, true},
+
        // Printf.
        {"printf", `{{printf "hello, printf"}}`, "hello, printf", tVal, true},
        {"printf int", `{{printf "%04x" 127}}`, "007f", tVal, true},
@@ -158,19 +204,23 @@ var execTests = []execTest{
        {"printf field", `{{printf "%s" .U.V}}`, "v", tVal, true},
        {"printf method", `{{printf "%s" .Method0}}`, "resultOfMethod0", tVal, true},
        {"printf lots", `{{printf "%d %s %g %s" 127 "hello" 7-3i .Method0}}`, "127 hello (7-3i) resultOfMethod0", tVal, true},
+
        // HTML.
        {"html", `{{html "<script>alert(\"XSS\");</script>"}}`,
                "&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
        {"html pipeline", `{{printf "<script>alert(\"XSS\");</script>" | html}}`,
                "&lt;script&gt;alert(&#34;XSS&#34;);&lt;/script&gt;", nil, true},
-       // JS.
+
+       // JavaScript.
        {"js", `{{js .}}`, `It\'d be nice.`, `It'd be nice.`, true},
+
        // Booleans
        {"not", "{{not true}} {{not false}}", "false true", nil, true},
        {"and", "{{and 0 0}} {{and 1 0}} {{and 0 1}} {{and 1 1}}", "false false false true", nil, true},
        {"or", "{{or 0 0}} {{or 1 0}} {{or 0 1}} {{or 1 1}}", "false true true true", nil, true},
        {"boolean if", "{{if and true 1 `hi`}}TRUE{{else}}FALSE{{end}}", "TRUE", tVal, true},
        {"boolean if not", "{{if and true 1 `hi` | not}}TRUE{{else}}FALSE{{end}}", "FALSE", nil, true},
+
        // Indexing.
        {"slice[0]", "{{index .SI 0}}", "3", tVal, true},
        {"slice[1]", "{{index .SI 1}}", "4", tVal, true},
@@ -181,6 +231,7 @@ var execTests = []execTest{
        {"map[NO]", "{{index .MSI `XXX`}}", "", tVal, false},
        {"map[WRONG]", "{{index .MSI 10}}", "", tVal, false},
        {"double index", "{{index .SMSI 1 `eleven`}}", "11", tVal, true},
+
        // With.
        {"with true", "{{with true}}{{.}}{{end}}", "true", tVal, true},
        {"with false", "{{with false}}{{.}}{{else}}FALSE{{end}}", "FALSE", tVal, true},
@@ -196,6 +247,8 @@ var execTests = []execTest{
        {"with slice", "{{with .SI}}{{.}}{{else}}EMPTY{{end}}", "[3 4 5]", tVal, true},
        {"with emptymap", "{{with .MSIEmpty}}{{.}}{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
        {"with map", "{{with .MSIone}}{{.}}{{else}}EMPTY{{end}}", "map[one:1]", tVal, true},
+       {"with empty interface, struct field", "{{with .Empty4}}{{.V}}{{end}}", "v", tVal, true},
+
        // Range.
        {"range []int", "{{range .SI}}-{{.}}-{{end}}", "-3--4--5-", tVal, true},
        {"range empty no else", "{{range .SIEmpty}}-{{.}}-{{end}}", "", tVal, true},
@@ -207,7 +260,8 @@ var execTests = []execTest{
        {"range empty map no else", "{{range .MSIEmpty}}-{{.}}-{{end}}", "", tVal, true},
        {"range map else", "{{range .MSI | .MSort}}-{{.}}-{{else}}EMPTY{{end}}", "-one--three--two-", tVal, true},
        {"range empty map else", "{{range .MSIEmpty}}-{{.}}-{{else}}EMPTY{{end}}", "EMPTY", tVal, true},
-       {"range empty interface", "{{range .EmptyInterface}}-{{.}}-{{else}}EMPTY{{end}}", "-7--8-", tVal, true},
+       {"range empty interface", "{{range .Empty3}}-{{.}}-{{else}}EMPTY{{end}}", "-7--8-", tVal, true},
+
        // Error handling.
        {"error method, error", "{{.EPERM true}}", "", tVal, false},
        {"error method, no error", "{{.EPERM false}}", "false", tVal, true},

diff --git a/src/pkg/exp/template/funcs.go b/src/pkg/exp/template/funcs.go
index 6d781beca8eec23960e737ea2a4a56f3d6efe4bd..66be40fd4d7724cd5e02cff728ecd93433eb85f9 100644 (file)
--- a/src/pkg/exp/template/funcs.go
+++ b/src/pkg/exp/template/funcs.go
@@ -83,6 +83,10 @@ func index(item interface{}, indices ...interface{}) (interface{}, os.Error) {
        v := reflect.ValueOf(item)
        for _, i := range indices {
                index := reflect.ValueOf(i)
+               var isNil bool
+               if v, isNil = indirect(v); isNil {
+                       return nil, fmt.Errorf("index of nil pointer")
+               }
                switch v.Kind() {
                case reflect.Array, reflect.Slice:
                        var x int64