text/template: add 'nil' as a keyword in the language
The keyword reprents an untyped nil and is useful for
passing nil values to methods and functions. The
nil will be promoted to the appropriate type when
used; if a type cannot be assigned, an error results.
R=rsc, dsymonds
CC=golang-dev
https://golang.org/cl/6459056
diff --git a/src/pkg/text/template/exec_test.go b/src/pkg/text/template/exec_test.go
index 4efe2d1..95e0592 100644
--- a/src/pkg/text/template/exec_test.go
+++ b/src/pkg/text/template/exec_test.go
@@ -63,6 +63,7 @@
BinaryFunc func(string, string) string
VariadicFunc func(...string) string
VariadicFuncInt func(int, ...string) string
+ NilOKFunc func(*int) bool
// Template to test evaluation of templates.
Tmpl *Template
// Unexported field; cannot be accessed by template.
@@ -127,6 +128,7 @@
BinaryFunc: func(a, b string) string { return fmt.Sprintf("[%s=%s]", a, b) },
VariadicFunc: func(s ...string) string { return fmt.Sprint("<", strings.Join(s, "+"), ">") },
VariadicFuncInt: func(a int, s ...string) string { return fmt.Sprint(a, "=<", strings.Join(s, "+"), ">") },
+ NilOKFunc: func(s *int) bool { return s == nil },
Tmpl: Must(New("x").Parse("test template")), // "x" is the value of .X
}
@@ -222,6 +224,7 @@
// Trivial cases.
{"empty", "", "", nil, true},
{"text", "some text", "some text", nil, true},
+ {"nil action", "{{nil}}", "", nil, false},
// Ideal constants.
{"ideal int", "{{typeOf 3}}", "int", 0, true},
@@ -230,6 +233,7 @@
{"ideal complex", "{{typeOf 1i}}", "complex128", 0, true},
{"ideal int", "{{typeOf " + bigInt + "}}", "int", 0, true},
{"ideal too big", "{{typeOf " + bigUint + "}}", "", 0, false},
+ {"ideal nil without type", "{{nil}}", "", 0, false},
// Fields of structs.
{".X", "-{{.X}}-", "-x-", tVal, true},
@@ -295,7 +299,8 @@
{".Method2(3, .X)", "-{{.Method2 3 .X}}-", "-Method2: 3 x-", tVal, true},
{".Method2(.U16, `str`)", "-{{.Method2 .U16 `str`}}-", "-Method2: 16 str-", tVal, true},
{".Method2(.U16, $x)", "{{if $x := .X}}-{{.Method2 .U16 $x}}{{end}}-", "-Method2: 16 x-", tVal, true},
- {".Method3(nil)", "-{{.Method3 .MXI.unset}}-", "-Method3: <nil>-", tVal, true},
+ {".Method3(nil constant)", "-{{.Method3 nil}}-", "-Method3: <nil>-", tVal, true},
+ {".Method3(nil value)", "-{{.Method3 .MXI.unset}}-", "-Method3: <nil>-", tVal, true},
{"method on var", "{{if $x := .}}-{{$x.Method2 .U16 $x.X}}{{end}}-", "-Method2: 16 x-", tVal, true},
{"method on chained var",
"{{range .MSIone}}{{if $.U.TrueFalse $.True}}{{$.U.TrueFalse $.True}}{{else}}WRONG{{end}}{{end}}",
@@ -306,6 +311,8 @@
{"chained method on variable",
"{{with $x := .}}{{with .SI}}{{$.GetU.TrueFalse $.True}}{{end}}{{end}}",
"true", tVal, true},
+ {".NilOKFunc not nil", "{{call .NilOKFunc .PI}}", "false", tVal, true},
+ {".NilOKFunc nil", "{{call .NilOKFunc nil}}", "true", tVal, true},
// Function call builtin.
{".BinaryFunc", "{{call .BinaryFunc `1` `2`}}", "[1=2]", tVal, true},
@@ -324,6 +331,7 @@
{".VariadicFuncBad0", "{{call .VariadicFunc 3}}", "", tVal, false},
{".VariadicFuncIntBad0", "{{call .VariadicFuncInt}}", "", tVal, false},
{".VariadicFuncIntBad`", "{{call .VariadicFuncInt `x`}}", "", tVal, false},
+ {".VariadicFuncNilBad", "{{call .VariadicFunc nil}}", "", tVal, false},
// Pipelines.
{"pipeline", "-{{.Method0 | .Method2 .U16}}-", "-Method2: 16 M0-", tVal, true},
@@ -332,6 +340,7 @@
// If.
{"if true", "{{if true}}TRUE{{end}}", "TRUE", tVal, true},
{"if false", "{{if false}}TRUE{{else}}FALSE{{end}}", "FALSE", tVal, true},
+ {"if nil", "{{if nil}}TRUE{{end}}", "", tVal, false},
{"if 1", "{{if 1}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
{"if 0", "{{if 0}}NON-ZERO{{else}}ZERO{{end}}", "ZERO", tVal, true},
{"if 1.5", "{{if 1.5}}NON-ZERO{{else}}ZERO{{end}}", "NON-ZERO", tVal, true},
@@ -351,7 +360,8 @@
// Print etc.
{"print", `{{print "hello, print"}}`, "hello, print", tVal, true},
- {"print", `{{print 1 2 3}}`, "1 2 3", tVal, true},
+ {"print 123", `{{print 1 2 3}}`, "1 2 3", tVal, true},
+ {"print nil", `{{print nil}}`, "<nil>", tVal, true},
{"println", `{{println 1 2 3}}`, "1 2 3\n", tVal, true},
{"printf int", `{{printf "%04x" 127}}`, "007f", tVal, true},
{"printf float", `{{printf "%g" 3.5}}`, "3.5", tVal, true},
@@ -391,6 +401,7 @@
{"map[one]", "{{index .MSI `one`}}", "1", tVal, true},
{"map[two]", "{{index .MSI `two`}}", "2", tVal, true},
{"map[NO]", "{{index .MSI `XXX`}}", "0", tVal, true},
+ {"map[nil]", "{{index .MSI nil}}", "0", tVal, true},
{"map[WRONG]", "{{index .MSI 10}}", "", tVal, false},
{"double index", "{{index .SMSI 1 `eleven`}}", "11", tVal, true},
