diff options
| -rwxr-xr-x | doc/pegdocs.txt | 6 | ||||
| -rwxr-xr-x | lib/pure/pegs.nim | 53 | ||||
| -rwxr-xr-x | web/news.txt | 1 |
3 files changed, 55 insertions, 5 deletions
diff --git a/doc/pegdocs.txt b/doc/pegdocs.txt index be47fa7b4..922b998c7 100755 --- a/doc/pegdocs.txt +++ b/doc/pegdocs.txt @@ -66,6 +66,10 @@ notation meaning failure. ``@E`` Search: Shorthand for ``(!E .)* E``. (Search loop for the pattern `E`.) +``{@} E`` Captured Search: Shorthand for ``{(!E .)*} E``. (Search + loop for the pattern `E`.) Everything until and exluding + `E` is captured. +``@@ E`` Same as ``{@} E``. ``A <- E`` Rule: Bind the expression `E` to the *nonterminal symbol* `A`. **Left recursive rules are not possible and crash the matching engine.** @@ -131,7 +135,7 @@ The PEG parser implements this grammar (written in PEG syntax):: rule <- identifier \s* "<-" expr ig identNoArrow <- identifier !(\s* "<-") - prefixOpr <- ig '&' / ig '!' / ig '@' + prefixOpr <- ig '&' / ig '!' / ig '@' / ig '{@}' / ig '@@' literal <- ig identifier? '$' [0-9]+ ig identNoArrow / ig charset / diff --git a/lib/pure/pegs.nim b/lib/pure/pegs.nim index 70d8d8d37..0a373125d 100755 --- a/lib/pure/pegs.nim +++ b/lib/pure/pegs.nim @@ -58,6 +58,7 @@ type pkBackRefIgnoreCase, pkBackRefIgnoreStyle, pkSearch, ## @a --> Internal DSL: @a + pkCapturedSearch, ## {@} a --> Internal DSL: @@a pkRule, ## a <- b pkList ## a, b TNonTerminalFlag = enum @@ -192,6 +193,11 @@ proc `@`*(a: TPeg): TPeg {.nosideEffect, rtl, extern: "npegsSearch".} = ## constructs a "search" for the PEG `a` result.kind = pkSearch result.sons = @[a] + +proc `@@`*(a: TPeg): TPeg {.noSideEffect, rtl, + extern: "npgegsCapturedSearch".} = + result.kind = pkCapturedSearch + result.sons = @[a] when false: proc contains(a: TPeg, k: TPegKind): bool = @@ -421,6 +427,9 @@ proc toStrAux(r: TPeg, res: var string) = of pkSearch: add(res, '@') toStrAux(r.sons[0], res) + of pkCapturedSearch: + add(res, "{@}") + toStrAux(r.sons[0], res) of pkCapture: add(res, '{') toStrAux(r.sons[0], res) @@ -558,6 +567,21 @@ proc m(s: string, p: TPeg, start: int, c: var TMatchClosure): int = inc(result) result = -1 c.ml = oldMl + of pkCapturedSearch: + var idx = c.ml # reserve a slot for the subpattern + inc(c.ml) + result = 0 + while start+result < s.len: + var x = m(s, p.sons[0], start+result, c) + if x >= 0: + if idx < maxSubpatterns: + c.matches[idx] = (start, start+result-1) + #else: silently ignore the capture + inc(result, x) + return + inc(result) + result = -1 + c.ml = idx of pkGreedyRep: result = 0 while true: @@ -850,6 +874,7 @@ type tkParRi, ## ')' tkCurlyLe, ## '{' tkCurlyRi, ## '}' + tkCurlyAt, ## '{@}' tkArrow, ## '<-' tkBar, ## '/' tkStar, ## '*' @@ -880,7 +905,8 @@ type const tokKindToStr: array[TTokKind, string] = [ "invalid", "[EOF]", ".", "_", "identifier", "string literal", - "character set", "(", ")", "{", "}", "<-", "/", "*", "+", "&", "!", "?", + "character set", "(", ")", "{", "}", "{@}", + "<-", "/", "*", "+", "&", "!", "?", "@", "built-in", "escaped", "$" ] @@ -1112,9 +1138,14 @@ proc getTok(c: var TPegLexer, tok: var TToken) = skip(c) case c.buf[c.bufpos] of '{': - tok.kind = tkCurlyLe inc(c.bufpos) - add(tok.literal, '{') + if c.buf[c.bufpos] == '@' and c.buf[c.bufpos+1] == '}': + tok.kind = tkCurlyAt + inc(c.bufpos, 2) + add(tok.literal, "{@}") + else: + tok.kind = tkCurlyLe + add(tok.literal, '{') of '}': tok.kind = tkCurlyRi inc(c.bufpos) @@ -1193,6 +1224,10 @@ proc getTok(c: var TPegLexer, tok: var TToken) = tok.kind = tkAt inc(c.bufpos) add(tok.literal, '@') + if c.buf[c.bufpos] == '@': + tok.kind = tkCurlyAt + inc(c.bufpos) + add(tok.literal, '@') else: add(tok.literal, c.buf[c.bufpos]) inc(c.bufpos) @@ -1261,6 +1296,9 @@ proc primary(p: var TPegParser): TPeg = of tkAt: getTok(p) return @primary(p) + of tkCurlyAt: + getTok(p) + return @@primary(p) else: nil case p.tok.kind of tkIdentifier: @@ -1346,7 +1384,7 @@ proc seqExpr(p: var TPegParser): TPeg = while true: case p.tok.kind of tkAmp, tkNot, tkAt, tkStringLit, tkCharset, tkParLe, tkCurlyLe, - tkAny, tkAnyRune, tkBuiltin, tkEscaped, tkDollar: + tkAny, tkAnyRune, tkBuiltin, tkEscaped, tkDollar, tkCurlyAt: result = sequence(result, primary(p)) of tkIdentifier: if not arrowIsNextTok(p): @@ -1514,4 +1552,11 @@ when isMainModule: for x in findAll("abcdef", peg"{.}", 3): echo x + + if "f(a, b)" =~ peg"{[0-9]+} / ({\ident} '(' {@} ')')": + assert matches[0] == "f" + assert matches[1] == "a, b" + else: + assert false + diff --git a/web/news.txt b/web/news.txt index d728a46d2..4e6c51c56 100755 --- a/web/news.txt +++ b/web/news.txt @@ -21,6 +21,7 @@ Additions - Added ``re.findAll``, ``pegs.findAll``. - Added ``os.findExe``. +- The Pegs module supports a *captured search loop operator* ``{@}``. 2010-10-20 Version 0.8.10 released |