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go spec: be precise with the use of the informal ellipsis … and the Go token ...

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Fixes #1867.

R=r
CC=golang-dev
https://golang.org/cl/4538092
This commit is contained in:
Robert Griesemer 2011-05-24 14:18:44 -07:00
parent 46f482a2fc
commit 3c7271f057
4 changed files with 32 additions and 26 deletions
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46
doc/go_spec.html
View File

@ -48,7 +48,7 @@ The syntax is specified using Extended Backus-Naur Form (EBNF):
Production = production_name "=" [ Expression ] "." .
Expression = Alternative { "|" Alternative } .
Alternative = Term { Term } .
Term = production_name | token [ "..." token ] | Group | Option | Repetition .
Term = production_name | token [ "…" token ] | Group | Option | Repetition .
Group = "(" Expression ")" .
Option = "[" Expression "]" .
Repetition = "{" Expression "}" .
@ -72,8 +72,12 @@ double quotes <code>""</code> or back quotes <code>``</code>.
</p>
<p>
The form <code>a ... b</code> represents the set of characters from
<code>a</code> through <code>b</code> as alternatives.
The form <code>a … b</code> represents the set of characters from
<code>a</code> through <code>b</code> as alternatives. The horizontal
ellipis … is also used elsewhere in the spec to informally denote various
enumerations or code snippets that are not further specified. The character …
(as opposed to the three characters <code>...</code>) is not a token of the Go
language.
</p>
<h2 id="Source_code_representation">Source code representation</h2>
@ -122,9 +126,9 @@ The underscore character <code>_</code> (U+005F) is considered a letter.
</p>
<pre class="ebnf">
letter = unicode_letter | "_" .
decimal_digit = "0" ... "9" .
octal_digit = "0" ... "7" .
hex_digit = "0" ... "9" | "A" ... "F" | "a" ... "f" .
decimal_digit = "0" … "9" .
octal_digit = "0" … "7" .
hex_digit = "0" … "9" | "A" … "F" | "a" … "f" .
</pre>
<h2 id="Lexical_elements">Lexical elements</h2>
@ -286,7 +290,7 @@ An optional prefix sets a non-decimal base: <code>0</code> for octal, <code>0x</
</p>
<pre class="ebnf">
int_lit = decimal_lit | octal_lit | hex_lit .
decimal_lit = ( "1" ... "9" ) { decimal_digit } .
decimal_lit = ( "1" … "9" ) { decimal_digit } .
octal_lit = "0" { octal_digit } .
hex_lit = "0" ( "x" | "X" ) hex_digit { hex_digit } .
</pre>
@ -1053,9 +1057,9 @@ have the method set
</p>
<pre>
func (p T) Read(b Buffer) bool { return ... }
func (p T) Write(b Buffer) bool { return ... }
func (p T) Close() { ... }
func (p T) Read(b Buffer) bool { return … }
func (p T) Write(b Buffer) bool { return … }
func (p T) Close() { … }
</pre>
<p>
@ -1093,8 +1097,8 @@ If <code>S1</code> and <code>S2</code> also implement
</p>
<pre>
func (p T) Lock() { ... }
func (p T) Unlock() { ... }
func (p T) Lock() { … }
func (p T) Unlock() { … }
</pre>
<p>
@ -2099,7 +2103,7 @@ element index plus one. A slice literal has the form
</p>
<pre>
[]T{x1, x2, ... xn}
[]T{x1, x2, … xn}
</pre>
<p>
@ -2107,7 +2111,7 @@ and is a shortcut for a slice operation applied to an array literal:
</p>
<pre>
[n]T{x1, x2, ... xn}[0 : n]
[n]T{x1, x2, … xn}[0 : n]
</pre>
<p>
@ -2133,8 +2137,8 @@ parentheses.
</p>
<pre>
if x == (T{a,b,c}[i]) { ... }
if (x == T{a,b,c}[i]) { ... }
if x == (T{a,b,c}[i]) { … }
if (x == T{a,b,c}[i]) { … }
</pre>
<p>
@ -2567,11 +2571,11 @@ Given an expression <code>f</code> of function type
</p>
<pre>
f(a1, a2, ... an)
f(a1, a2, … an)
</pre>
<p>
calls <code>f</code> with arguments <code>a1, a2, ... an</code>.
calls <code>f</code> with arguments <code>a1, a2, … an</code>.
Except for one special case, arguments must be single-valued expressions
<a href="#Assignability">assignable</a> to the parameter types of
<code>F</code> and are evaluated before the function is called.
@ -2650,7 +2654,7 @@ arguments bound to the final parameter and may differ for each call site.
Given the function and call
</p>
<pre>
func Greeting(prefix string, who ... string)
func Greeting(prefix string, who ...string)
Greeting("hello:", "Joe", "Anna", "Eileen")
</pre>
@ -4891,7 +4895,7 @@ package main
import "fmt"
// Send the sequence 2, 3, 4, ... to channel 'ch'.
// Send the sequence 2, 3, 4, … to channel 'ch'.
func generate(ch chan&lt;- int) {
for i := 2; ; i++ {
ch &lt;- i // Send 'i' to channel 'ch'.
@ -5042,7 +5046,7 @@ arguments and returns no value.
</p>
<pre>
func main() { ... }
func main() { … }
</pre>
<p>

5
src/cmd/godoc/spec.go
View File

@ -99,7 +99,8 @@ func (p *ebnfParser) parseTerm() bool {
case token.STRING:
p.next()
if p.tok == token.ELLIPSIS {
const ellipsis = "…" // U+2026, the horizontal ellipsis character
if p.tok == token.ILLEGAL && p.lit == ellipsis {
p.next()
p.expect(token.STRING)
}
@ -157,7 +158,7 @@ func (p *ebnfParser) parse(fset *token.FileSet, out io.Writer, src []byte) {
p.out = out
p.src = src
p.file = fset.AddFile("", fset.Base(), len(src))
p.scanner.Init(p.file, src, p, 0)
p.scanner.Init(p.file, src, p, scanner.AllowIllegalChars)
p.next() // initializes pos, tok, lit
// process source

2
src/pkg/ebnf/ebnf_test.go
View File

@ -22,7 +22,7 @@ var grammars = []string{
`Program = "a" | "b" "c" .`,
`Program = "a" ... "z" .`,
`Program = "a" … "z" .`,
`Program = Song .
Song = { Note } .

5
src/pkg/ebnf/parser.go
View File

@ -95,7 +95,8 @@ func (p *parser) parseTerm() (x Expression) {
case token.STRING:
tok := p.parseToken()
x = tok
if p.tok == token.ELLIPSIS {
const ellipsis = "…" // U+2026, the horizontal ellipsis character
if p.tok == token.ILLEGAL && p.lit == ellipsis {
p.next()
x = &Range{tok, p.parseToken()}
}
@ -177,7 +178,7 @@ func (p *parser) parse(fset *token.FileSet, filename string, src []byte) Grammar
// initialize parser
p.fset = fset
p.ErrorVector.Reset()
p.scanner.Init(fset.AddFile(filename, fset.Base(), len(src)), src, p, 0)
p.scanner.Init(fset.AddFile(filename, fset.Base(), len(src)), src, p, scanner.AllowIllegalChars)
p.next() // initializes pos, tok, lit
grammar := make(Grammar)