From 238274ede0ec19e6a8b83334b5c6729afa746beb Mon Sep 17 00:00:00 2001 From: Rob Pike Date: Thu, 7 Jul 2011 14:51:35 +1000 Subject: [PATCH] exp/template: handle pointers and values in empty interfaces. R=golang-dev, r, mattn.jp CC=golang-dev https://golang.org/cl/4664064 --- src/pkg/exp/template/exec.go | 25 ++++++-- src/pkg/exp/template/exec_test.go | 94 ++++++++++++++++++++++++------- src/pkg/exp/template/funcs.go | 4 ++ 3 files changed, 98 insertions(+), 25 deletions(-) diff --git a/src/pkg/exp/template/exec.go b/src/pkg/exp/template/exec.go index 6f171da384..fb0a9e6218 100644 --- 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, "") 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, "") + 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 f974673d44..8992299ebf 100644 --- 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}}", "", tVal, true}, + + // Emtpy interfaces holding values. + {"empty nil", "{{.Empty0}}", "", 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>", nil, true}, {"html pipeline", `{{printf "" | html}}`, "<script>alert("XSS");</script>", 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 6d781beca8..66be40fd4d 100644 --- 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