summaryrefslogtreecommitdiff
path: root/libgo/go/text/template/parse/lex.go
diff options
context:
space:
mode:
Diffstat (limited to 'libgo/go/text/template/parse/lex.go')
-rw-r--r--libgo/go/text/template/parse/lex.go240
1 files changed, 139 insertions, 101 deletions
diff --git a/libgo/go/text/template/parse/lex.go b/libgo/go/text/template/parse/lex.go
index c4e1a56a8d4..23c0cf0793c 100644
--- a/libgo/go/text/template/parse/lex.go
+++ b/libgo/go/text/template/parse/lex.go
@@ -13,8 +13,9 @@ import (
// item represents a token or text string returned from the scanner.
type item struct {
- typ itemType
- val string
+ typ itemType // The type of this item.
+ pos Pos // The starting position, in bytes, of this item in the input string.
+ val string // The value of this item.
}
func (i item) String() string {
@@ -42,65 +43,32 @@ const (
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
+ itemField // alphanumeric identifier starting with '.'
+ itemIdentifier // alphanumeric identifier not starting with '.'
itemLeftDelim // left action delimiter
+ itemLeftParen // '(' inside action
itemNumber // simple number, including imaginary
itemPipe // pipe symbol
itemRawString // raw quoted string (includes quotes)
itemRightDelim // right action delimiter
+ itemRightParen // ')' inside action
+ itemSpace // run of spaces separating arguments
itemString // quoted string (includes quotes)
itemText // plain text
- itemVariable // variable starting with '$', such as '$' or '$1' or '$hello'.
+ 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 '.'.
+ itemDot // the cursor, spelled '.'
itemDefine // define keyword
itemElse // else keyword
itemEnd // end keyword
itemIf // if keyword
+ itemNil // the untyped nil constant, easiest to treat as a keyword
itemRange // range keyword
itemTemplate // template keyword
itemWith // with keyword
)
-// Make the types prettyprint.
-var itemName = map[itemType]string{
- itemError: "error",
- itemBool: "bool",
- itemChar: "char",
- itemCharConstant: "charconst",
- 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",
- itemElse: "else",
- itemIf: "if",
- itemEnd: "end",
- itemRange: "range",
- itemTemplate: "template",
- itemWith: "with",
-}
-
-func (i itemType) String() string {
- s := itemName[i]
- if s == "" {
- return fmt.Sprintf("item%d", int(i))
- }
- return s
-}
-
var key = map[string]itemType{
".": itemDot,
"define": itemDefine,
@@ -108,6 +76,7 @@ var key = map[string]itemType{
"end": itemEnd,
"if": itemIf,
"range": itemRange,
+ "nil": itemNil,
"template": itemTemplate,
"with": itemWith,
}
@@ -119,24 +88,27 @@ type stateFn func(*lexer) stateFn
// lexer holds the state of the scanner.
type lexer struct {
- name string // the name of the input; used only for error reports.
- input string // the string being scanned.
- leftDelim string // start of action.
- rightDelim string // end of action.
- state stateFn // the next lexing function to enter.
- pos int // current position in the input.
- start int // start position of this item.
- width int // width of last rune read from input.
- items chan item // channel of scanned items.
+ name string // the name of the input; used only for error reports
+ input string // the string being scanned
+ leftDelim string // start of action
+ rightDelim string // end of action
+ state stateFn // the next lexing function to enter
+ pos Pos // current position in the input
+ start Pos // start position of this item
+ width Pos // width of last rune read from input
+ lastPos Pos // position of most recent item returned by nextItem
+ items chan item // channel of scanned items
+ parenDepth int // nesting depth of ( ) exprs
}
// next returns the next rune in the input.
-func (l *lexer) next() (r rune) {
- if l.pos >= len(l.input) {
+func (l *lexer) next() rune {
+ if int(l.pos) >= len(l.input) {
l.width = 0
return eof
}
- r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
+ r, w := utf8.DecodeRuneInString(l.input[l.pos:])
+ l.width = Pos(w)
l.pos += l.width
return r
}
@@ -155,7 +127,7 @@ func (l *lexer) backup() {
// emit passes an item back to the client.
func (l *lexer) emit(t itemType) {
- l.items <- item{t, l.input[l.start:l.pos]}
+ l.items <- item{t, l.start, l.input[l.start:l.pos]}
l.start = l.pos
}
@@ -180,30 +152,25 @@ func (l *lexer) acceptRun(valid string) {
l.backup()
}
-// lineNumber reports which line we're on. Doing it this way
+// lineNumber reports which line we're on, based on the position of
+// the previous item returned by nextItem. Doing it this way
// means we don't have to worry about peek double counting.
func (l *lexer) lineNumber() int {
- return 1 + strings.Count(l.input[:l.pos], "\n")
+ return 1 + strings.Count(l.input[:l.lastPos], "\n")
}
-// error returns an error token and terminates the scan by passing
+// errorf returns an error token and terminates the scan by passing
// back a nil pointer that will be the next state, terminating l.nextItem.
func (l *lexer) errorf(format string, args ...interface{}) stateFn {
- l.items <- item{itemError, fmt.Sprintf(format, args...)}
+ l.items <- item{itemError, l.start, fmt.Sprintf(format, args...)}
return nil
}
// nextItem returns the next item from the input.
func (l *lexer) nextItem() item {
- for {
- select {
- case item := <-l.items:
- return item
- default:
- l.state = l.state(l)
- }
- }
- panic("not reached")
+ item := <-l.items
+ l.lastPos = item.pos
+ return item
}
// lex creates a new scanner for the input string.
@@ -219,12 +186,19 @@ func lex(name, input, left, right string) *lexer {
input: input,
leftDelim: left,
rightDelim: right,
- state: lexText,
- items: make(chan item, 2), // Two items of buffering is sufficient for all state functions
+ items: make(chan item),
}
+ go l.run()
return l
}
+// run runs the state machine for the lexer.
+func (l *lexer) run() {
+ for l.state = lexText; l.state != nil; {
+ l.state = l.state(l)
+ }
+}
+
// state functions
const (
@@ -257,29 +231,30 @@ func lexText(l *lexer) stateFn {
// lexLeftDelim scans the left delimiter, which is known to be present.
func lexLeftDelim(l *lexer) stateFn {
- l.pos += len(l.leftDelim)
+ l.pos += Pos(len(l.leftDelim))
if strings.HasPrefix(l.input[l.pos:], leftComment) {
return lexComment
}
l.emit(itemLeftDelim)
+ l.parenDepth = 0
return lexInsideAction
}
// lexComment scans a comment. The left comment marker is known to be present.
func lexComment(l *lexer) stateFn {
- l.pos += len(leftComment)
+ l.pos += Pos(len(leftComment))
i := strings.Index(l.input[l.pos:], rightComment+l.rightDelim)
if i < 0 {
return l.errorf("unclosed comment")
}
- l.pos += i + len(rightComment) + len(l.rightDelim)
+ l.pos += Pos(i + len(rightComment) + len(l.rightDelim))
l.ignore()
return lexText
}
// lexRightDelim scans the right delimiter, which is known to be present.
func lexRightDelim(l *lexer) stateFn {
- l.pos += len(l.rightDelim)
+ l.pos += Pos(len(l.rightDelim))
l.emit(itemRightDelim)
return lexText
}
@@ -287,16 +262,19 @@ func lexRightDelim(l *lexer) stateFn {
// lexInsideAction scans the elements inside action delimiters.
func lexInsideAction(l *lexer) stateFn {
// Either number, quoted string, or identifier.
- // Spaces separate and are ignored.
+ // Spaces separate arguments; runs of spaces turn into itemSpace.
// Pipe symbols separate and are emitted.
if strings.HasPrefix(l.input[l.pos:], l.rightDelim) {
- return lexRightDelim
+ if l.parenDepth == 0 {
+ return lexRightDelim
+ }
+ return l.errorf("unclosed left paren")
}
switch r := l.next(); {
- case r == eof || r == '\n':
+ case r == eof || isEndOfLine(r):
return l.errorf("unclosed action")
case isSpace(r):
- l.ignore()
+ return lexSpace
case r == ':':
if l.next() != '=' {
return l.errorf("expected :=")
@@ -309,15 +287,15 @@ func lexInsideAction(l *lexer) stateFn {
case r == '`':
return lexRawQuote
case r == '$':
- return lexIdentifier
+ return lexVariable
case r == '\'':
return lexChar
case r == '.':
// special look-ahead for ".field" so we don't break l.backup().
- if l.pos < len(l.input) {
+ if l.pos < Pos(len(l.input)) {
r := l.input[l.pos]
if r < '0' || '9' < r {
- return lexIdentifier // itemDot comes from the keyword table.
+ return lexField
}
}
fallthrough // '.' can start a number.
@@ -327,6 +305,17 @@ func lexInsideAction(l *lexer) stateFn {
case isAlphaNumeric(r):
l.backup()
return lexIdentifier
+ case r == '(':
+ l.emit(itemLeftParen)
+ l.parenDepth++
+ return lexInsideAction
+ case r == ')':
+ l.emit(itemRightParen)
+ l.parenDepth--
+ if l.parenDepth < 0 {
+ return l.errorf("unexpected right paren %#U", r)
+ }
+ return lexInsideAction
case r <= unicode.MaxASCII && unicode.IsPrint(r):
l.emit(itemChar)
return lexInsideAction
@@ -336,28 +325,34 @@ func lexInsideAction(l *lexer) stateFn {
return lexInsideAction
}
-// lexIdentifier scans an alphanumeric or field.
+// lexSpace scans a run of space characters.
+// One space has already been seen.
+func lexSpace(l *lexer) stateFn {
+ for isSpace(l.peek()) {
+ l.next()
+ }
+ l.emit(itemSpace)
+ return lexInsideAction
+}
+
+// lexIdentifier scans an alphanumeric.
func lexIdentifier(l *lexer) stateFn {
Loop:
for {
switch r := l.next(); {
case isAlphaNumeric(r):
// absorb.
- case r == '.' && (l.input[l.start] == '.' || l.input[l.start] == '$'):
- // field chaining; absorb into one token.
default:
l.backup()
word := l.input[l.start:l.pos]
if !l.atTerminator() {
- return l.errorf("unexpected character %+U", r)
+ return l.errorf("bad character %#U", r)
}
switch {
case key[word] > itemKeyword:
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:
@@ -369,17 +364,59 @@ Loop:
return lexInsideAction
}
+// lexField scans a field: .Alphanumeric.
+// The . has been scanned.
+func lexField(l *lexer) stateFn {
+ return lexFieldOrVariable(l, itemField)
+}
+
+// lexVariable scans a Variable: $Alphanumeric.
+// The $ has been scanned.
+func lexVariable(l *lexer) stateFn {
+ if l.atTerminator() { // Nothing interesting follows -> "$".
+ l.emit(itemVariable)
+ return lexInsideAction
+ }
+ return lexFieldOrVariable(l, itemVariable)
+}
+
+// lexVariable scans a field or variable: [.$]Alphanumeric.
+// The . or $ has been scanned.
+func lexFieldOrVariable(l *lexer, typ itemType) stateFn {
+ if l.atTerminator() { // Nothing interesting follows -> "." or "$".
+ if typ == itemVariable {
+ l.emit(itemVariable)
+ } else {
+ l.emit(itemDot)
+ }
+ return lexInsideAction
+ }
+ var r rune
+ for {
+ r = l.next()
+ if !isAlphaNumeric(r) {
+ l.backup()
+ break
+ }
+ }
+ if !l.atTerminator() {
+ return l.errorf("bad character %#U", r)
+ }
+ l.emit(typ)
+ return lexInsideAction
+}
+
// atTerminator reports whether the input is at valid termination character to
-// appear after an identifier. Mostly to catch cases like "$x+2" not being
-// acceptable without a space, in case we decide one day to implement
-// arithmetic.
+// appear after an identifier. Breaks .X.Y into two pieces. Also catches cases
+// like "$x+2" not being acceptable without a space, in case we decide one
+// day to implement arithmetic.
func (l *lexer) atTerminator() bool {
r := l.peek()
- if isSpace(r) {
+ if isSpace(r) || isEndOfLine(r) {
return true
}
switch r {
- case eof, ',', '|', ':':
+ case eof, '.', ',', '|', ':', ')', '(':
return true
}
// Does r start the delimiter? This can be ambiguous (with delim=="//", $x/2 will
@@ -392,7 +429,7 @@ func (l *lexer) atTerminator() bool {
}
// lexChar scans a character constant. The initial quote is already
-// scanned. Syntax checking is done by the parse.
+// scanned. Syntax checking is done by the parser.
func lexChar(l *lexer) stateFn {
Loop:
for {
@@ -412,7 +449,7 @@ Loop:
return lexInsideAction
}
-// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
+// lexNumber scans a number: decimal, octal, hex, float, or imaginary. This
// isn't a perfect number scanner - for instance it accepts "." and "0x0.2"
// and "089" - but when it's wrong the input is invalid and the parser (via
// strconv) will notice.
@@ -421,7 +458,7 @@ func lexNumber(l *lexer) stateFn {
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
if sign := l.peek(); sign == '+' || sign == '-' {
- // Complex: 1+2i. No spaces, must end in 'i'.
+ // Complex: 1+2i. No spaces, must end in 'i'.
if !l.scanNumber() || l.input[l.pos-1] != 'i' {
return l.errorf("bad number syntax: %q", l.input[l.start:l.pos])
}
@@ -495,11 +532,12 @@ Loop:
// isSpace reports whether r is a space character.
func isSpace(r rune) bool {
- switch r {
- case ' ', '\t', '\n', '\r':
- return true
- }
- return false
+ return r == ' ' || r == '\t'
+}
+
+// isEndOfLine reports whether r is an end-of-line character.
+func isEndOfLine(r rune) bool {
+ return r == '\r' || r == '\n'
}
// isAlphaNumeric reports whether r is an alphabetic, digit, or underscore.
View Lorry Controller Status