mirror of
https://github.com/AleoHQ/leo.git
synced 2024-12-01 02:08:31 +03:00
be more specific of where this grammar applies, clean up
This commit is contained in:
gluaxspeed
parent
2544a680f1
commit
3a6e4cb994
Binary file not shown.
@ -16,154 +16,25 @@
|
||||
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
|
||||
; Introduction
|
||||
; ------------
|
||||
|
||||
; This file contains an ABNF (Augmented Backus-Naur Form) grammar of Leo string formatting.
|
||||
; Background on ABNF is provided later in this file.
|
||||
|
||||
; This grammar provides an official definition of how format strings
|
||||
; are parsed for printed by the Leo compiler.
|
||||
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
|
||||
; Background on ABNF
|
||||
; ------------------
|
||||
|
||||
; ABNF is an Internet standard:
|
||||
; see RFC 5234 at https://www.rfc-editor.org/info/rfc5234
|
||||
; and RFC 7405 at https://www.rfc-editor.org/info/rfc7405.
|
||||
; It is used to specify the syntax of JSON, HTTP, and other standards.
|
||||
|
||||
; ABNF adds conveniences and makes slight modifications
|
||||
; to Backus-Naur Form (BNF),
|
||||
; without going beyond context-free grammars.
|
||||
|
||||
; Instead of BNF's angle-bracket notation for nonterminals,
|
||||
; ABNF uses case-insensitive names consisting of letters, digits, and dashes,
|
||||
; e.g. `HTTP-message` and `IPv6address`.
|
||||
; ABNF includes an angle-bracket notation for prose descriptions,
|
||||
; e.g. `<host, see [RFC3986], Section 3.2.2>`,
|
||||
; usable as last resort in the definiens of a nonterminal.
|
||||
|
||||
; While BNF allows arbitrary terminals,
|
||||
; ABNF uses only natural numbers as terminals,
|
||||
; and denotes them via:
|
||||
; (i) binary, decimal, or hexadecimal sequences,
|
||||
; e.g. `%b1.11.1010`, `%d1.3.10`, and `%x.1.3.A`
|
||||
; all denote the sequence of terminals [1, 3, 10];
|
||||
; (ii) binary, decimal, or hexadecimal ranges,
|
||||
; e.g. `%x30-39` denotes any singleton sequence of terminals
|
||||
; [_n_] with 48 <= _n_ <= 57 (an ASCII digit);
|
||||
; (iii) case-sensitive ASCII strings,
|
||||
; e.g. `%s"Ab"` denotes the sequence of terminals [65, 98];
|
||||
; and (iv) case-insensitive ASCII strings,
|
||||
; e.g. `%i"ab"`, or just `"ab"`, denotes
|
||||
; any sequence of terminals among
|
||||
; [65, 66],
|
||||
; [65, 98],
|
||||
; [97, 66], and
|
||||
; [97, 98].
|
||||
; ABNF terminals in suitable sets represent ASCII or Unicode characters.
|
||||
|
||||
; ABNF allows repetition prefixes `n*m`,
|
||||
; where `n` and `m` are natural numbers in decimal notation;
|
||||
; if absent,
|
||||
; `n` defaults to 0, and
|
||||
; `m` defaults to infinity.
|
||||
; For example,
|
||||
; `1*4HEXDIG` denotes one to four `HEXDIG`s,
|
||||
; `*3DIGIT` denotes up to three `DIGIT`s, and
|
||||
; `1*OCTET` denotes one or more `OCTET`s.
|
||||
; A single `n` prefix
|
||||
; abbreviates `n*n`,
|
||||
; e.g. `3DIGIT` denotes three `DIGIT`s.
|
||||
|
||||
; Instead of BNF's `|`, ABNF uses `/` to separate alternatives.
|
||||
; Repetition prefixes have precedence over juxtapositions,
|
||||
; which have precedence over `/`.
|
||||
; Round brackets group things and override the aforementioned precedence rules,
|
||||
; e.g. `*(WSP / CRLF WSP)` denotes sequences of terminals
|
||||
; obtained by repeating, zero or more times,
|
||||
; either (i) a `WSP` or (ii) a `CRLF` followed by a `WSP`.
|
||||
; Square brackets also group things but make them optional,
|
||||
; e.g. `[":" port]` is equivalent to `0*1(":" port)`.
|
||||
|
||||
; Instead of BNF's `::=`, ABNF uses `=` to define nonterminals,
|
||||
; and `=/` to incrementally add alternatives
|
||||
; to previously defined nonterminals.
|
||||
; For example, the rule `BIT = "0" / "1"`
|
||||
; is equivalent to `BIT = "0"` followed by `BIT =/ "1"`.
|
||||
|
||||
; The syntax of ABNF itself is formally specified in ABNF
|
||||
; (in Section 4 of the aforementioned RFC 5234,
|
||||
; after the syntax and semantics of ABNF
|
||||
; are informally specified in natural language
|
||||
; (in Sections 1, 2, and 3 of the aforementioned RFC 5234).
|
||||
; The syntax rules of ABNF prescribe the ASCII codes allowed for
|
||||
; white space (spaces and horizontal tabs),
|
||||
; line endings (carriage returns followed by line feeds),
|
||||
; and comments (semicolons to line endings).
|
||||
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
|
||||
; Structure
|
||||
; ---------
|
||||
|
||||
; This ABNF grammar consists of one grammar:
|
||||
; that describes how a Leo string-literal is parsed
|
||||
; for formatting.
|
||||
; for more info please checkout the
|
||||
; [README](./README.md) in this directory.
|
||||
|
||||
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
||||
|
||||
; Format String
|
||||
; -------------------
|
||||
|
||||
not-double-quote-or-backslash-or-brace = %x0-21
|
||||
/ %x23-5B
|
||||
/ %x5D-7A
|
||||
/ %x7C
|
||||
/ %x7E-10FFFF
|
||||
; anything but " or \ or { or }
|
||||
; This ABNF grammar consists of one grammar:
|
||||
; that describes how a Leo string-literal is parsed
|
||||
; for formatting. Meaning in this context
|
||||
; all characters are already parsed and we don't
|
||||
; have to worry about escapes or etc.
|
||||
|
||||
double-quote = %x22 ; "
|
||||
|
||||
single-quote = %x27 ; '
|
||||
|
||||
single-quote-escape = "\" single-quote ; \'
|
||||
|
||||
double-quote-escape = "\" double-quote ; \"
|
||||
|
||||
backslash-escape = "\\"
|
||||
|
||||
line-feed-escape = %s"\n"
|
||||
|
||||
carriage-return-escape = %s"\r"
|
||||
|
||||
horizontal-tab-escape = %s"\t"
|
||||
|
||||
null-character-escape = "\0"
|
||||
|
||||
simple-character-escape = single-quote-escape
|
||||
/ double-quote-escape
|
||||
/ backslash-escape
|
||||
/ line-feed-escape
|
||||
/ carriage-return-escape
|
||||
/ horizontal-tab-escape
|
||||
/ null-character-escape
|
||||
|
||||
octal-digit = %x30-37 ; 0-7
|
||||
|
||||
hexadecimal-digit = digit / "a" / "b" / "c" / "d" / "e" / "f"
|
||||
|
||||
ascii-character-escape = %s"\x" octal-digit hexadecimal-digit
|
||||
|
||||
unicode-character-escape = %s"\u{" 1*6hexadecimal-digit "}"
|
||||
|
||||
format-string-element-not-brace = not-double-quote-or-backslash-or-brace
|
||||
/ simple-character-escape
|
||||
/ ascii-character-escape
|
||||
/ unicode-character-escape
|
||||
not-brace = %x0-7A / %x7C / %x7E-10FFFF ; anything but { or }
|
||||
|
||||
format-string-container = "{}"
|
||||
|
||||
@ -171,9 +42,9 @@ format-string-open-brace = "{{"
|
||||
|
||||
format-string-close-brace = "}}"
|
||||
|
||||
format-string-element = format-string-element-not-brace
|
||||
format-string-element = not-brace
|
||||
/ format-string-container
|
||||
/ format-string-open-brace
|
||||
/ format-string-close-brace
|
||||
|
||||
format-string = double-quote *format-string-element double-quote
|
||||
format-string = *format-string-element
|
||||
|
||||
Loading…
Reference in New Issue
Block a user