exp/template: lex variables

Variables start with'$' and are declared with ':='.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/4662084

diff --git a/src/pkg/exp/template/lex.go b/src/pkg/exp/template/lex.go
index d78152979f248f9986f8149e2e6a2785dbd45af9..e8763c55c6b7e98fdf728fcca84de1962e67def2 100644 (file)
--- a/src/pkg/exp/template/lex.go
+++ b/src/pkg/exp/template/lex.go
@@ -35,9 +35,10 @@ func (i item) String() string {
 type itemType int
 
 const (
-       itemError   itemType = iota // error occurred; value is text of error
-       itemBool                    // boolean constant
-       itemComplex                 // complex constant (1+2i); imaginary is just a number
+       itemError       itemType = iota // error occurred; value is text of error
+       itemBool                        // boolean constant
+       itemComplex                     // complex constant (1+2i); imaginary is just a number
+       itemColonEquals                 // colon-equals (':=') introducing a declaration
        itemEOF
        itemField      // alphanumeric identifier, starting with '.', possibly chained ('.x.y')
        itemIdentifier // alphanumeric identifier
@@ -48,6 +49,7 @@ const (
        itemRightDelim // right action delimiter
        itemString     // quoted string (includes quotes)
        itemText       // plain text
+       itemVariable   // variable starting with '$', such as '$' or  '$1' or '$hello'.
        // Keywords appear after all the rest.
        itemKeyword  // used only to delimit the keywords
        itemDot      // the cursor, spelled '.'.
@@ -62,18 +64,20 @@ const (
 
 // Make the types prettyprint.
 var itemName = map[itemType]string{
-       itemError:      "error",
-       itemBool:       "bool",
-       itemComplex:    "complex",
-       itemEOF:        "EOF",
-       itemField:      "field",
-       itemIdentifier: "identifier",
-       itemLeftDelim:  "left delim",
-       itemNumber:     "number",
-       itemPipe:       "pipe",
-       itemRawString:  "raw string",
-       itemRightDelim: "right delim",
-       itemString:     "string",
+       itemError:       "error",
+       itemBool:        "bool",
+       itemComplex:     "complex",
+       itemColonEquals: ":=",
+       itemEOF:         "EOF",
+       itemField:       "field",
+       itemIdentifier:  "identifier",
+       itemLeftDelim:   "left delim",
+       itemNumber:      "number",
+       itemPipe:        "pipe",
+       itemRawString:   "raw string",
+       itemRightDelim:  "right delim",
+       itemString:      "string",
+       itemVariable:    "variable",
        // keywords
        itemDot:      ".",
        itemDefine:   "define",
@@ -279,12 +283,19 @@ func lexInsideAction(l *lexer) stateFn {
                        return l.errorf("unclosed action")
                case isSpace(r):
                        l.ignore()
+               case r == ':':
+                       if l.next() != '=' {
+                               return l.errorf("expected :=")
+                       }
+                       l.emit(itemColonEquals)
                case r == '|':
                        l.emit(itemPipe)
                case r == '"':
                        return lexQuote
                case r == '`':
                        return lexRawQuote
+               case r == '$':
+                       return lexIdentifier
                case r == '.':
                        // special look-ahead for ".field" so we don't break l.backup().
                        if l.pos < len(l.input) {
@@ -324,6 +335,8 @@ Loop:
                                l.emit(key[word])
                        case word[0] == '.':
                                l.emit(itemField)
+                       case word[0] == '$':
+                               l.emit(itemVariable)
                        case word == "true", word == "false":
                                l.emit(itemBool)
                        default:

diff --git a/src/pkg/exp/template/lex_test.go b/src/pkg/exp/template/lex_test.go
index 256ec04d853abc569367891f3cb2f2f7f7b15a73..d2156fa71291957bd0e28995e79d5388a857329f 100644 (file)
--- a/src/pkg/exp/template/lex_test.go
+++ b/src/pkg/exp/template/lex_test.go
@@ -85,6 +85,19 @@ var lexTests = []lexTest{
                tRight,
                tEOF,
        }},
+       {"variables", "{{$c := printf $ $hello $23 $.Method}}", []item{
+               tLeft,
+               {itemVariable, "$c"},
+               {itemColonEquals, ":="},
+               {itemIdentifier, "printf"},
+               {itemVariable, "$"},
+               {itemVariable, "$hello"},
+               {itemVariable, "$23"},
+               {itemVariable, "$"},
+               {itemField, ".Method"},
+               tRight,
+               tEOF,
+       }},
        {"pipeline", `intro {{echo hi 1.2 |noargs|args 1 "hi"}} outro`, []item{
                {itemText, "intro "},
                tLeft,