19 O Libro de Ridgun
A lib regex — Motor de Expresións Regulares Thompson NFA en Tempo Lineal $O(N \cdot M)$
19.1. Por que existe a lib regex? (O problema real e a filosofía Ridgun)
«Por que necesito unha lib
regexescrita dende cero en Ridgun puro en vez de enlazar unha librería de C de toda a vida?»
Esa é a primeira pregunta que se fai calquera enxeñeiro de sistemas ao chegar a regex. E a resposta resume toda a filosofía de ridgun-libs:
Sexamos sinceros: os motores de expresións regulares con backtracking teñen causado caídas globais famosas (coma en Cloudflare ou StackOverflow) cando un padrón coma (a+)+b recibe trinta a seguidas e entra en tempo exponencial $O(2^N)$.
A lib regex compila as túas expresións regulares (., *, +, ?, |, (), [a-z], [^...], ^, $, \d, \w, \s) a un autómata finito non determinista de Thompson (NFA) e avanza o conxunto de estados paso a paso en tempo estritamente lineal $O(N \cdot M)$, facendo que os ataques ReDoS sexan matematicamente imposibles.
Nun ecosistema tradicional, resolver as tarefas do dominio REGEX implica arrastrar dependencias externas en C, loitar con punteiros crus, conversións opacas de tipos, excepcións non verificadas ou pausas impredicibles do colector de lixo. En Ridgun, a lib regex (src/main/ridgun/lib/regex.rg) aborda o problema con catro principios innegociables:
- Declara
import regex(ouimport regex as alias) ao inicio do ficheiro: cada lib define o seu espazo de nomesmodule :: regexe en modo--strictas funcións multi-palabra invócanse sempre con espazos naturais. - Encadea as túas tubaxes de esquerda a dereita con
->: escribeentrada paso un -> paso dous -> resultado, usa máscaras(+ _ _ +)para desestruturar secuencias e omite_ =en sentenzas secuenciais (ou descarta con-> ()). - Recursión de cola con TCO (Tail-Call Optimization): todos os percorridos internos de
regexcompílanse a bucles nativos en espazo de pila $O(1)$. - Memoria determinista (
RMM1/RMM2): cada estrutura intermedia libérase no instante exacto en que remata a súa última lectura, sen Garbage Collector.
19.2. Artefactos nativos, importación e catálogo completo da API de regex
En ridgun-libs, regex é unha lib de primeira clase situada en src/main/ridgun/lib/regex.rg (dominio REGEX). Ao compilar con stable bundle, empaquétase en tres formatos nativos:
| Artefacto | Ruta | Propósito |
|---|---|---|
| Bundle Ridgun | target/bundles/regex.rglib | Distribución e importación directa con import regex |
| Ficheiro compilado | target/regex.rgc | Artefacto intermedio verificado por ridgunc |
| Obxecto compartido ELF64 | target/libregex.so | Biblioteca dinámica nativa sen dependencias de C nin libc |
Cada lib declara o seu propio espazo de nomes con
module :: regex: abonda con escribirimport regex(ouimport regex as alias) na cabeceira e chamar ás súas funcións con espazos naturais (mina funcion x) e tubaxes->(x mina funcion -> resultado).
19.2.1. Resumo de familias funcionais de regex
| Sinatura / Función / Tipo | Que fai e cando usala |
|---|---|
regex match / regex is match | Coincidencia de cadea completa e busca de subcadea en tempo lineal $O(N \cdot M)$ |
regex find / regex find all | Extrae a primeira ou todas as subcadeas coincidentes sen solapamento |
regex replace / regex replace all | Substitúe a primeira ou todas as coincidencias da expresión regular |
regex split / regex escape | Divide texto segundo un delimitador regex e escapa metacaracteres |
19.2.2. Catálogo exhaustivo de tipos e sinaturas en src/main/ridgun/lib/regex.rg
A continuación tes o inventario completo de tipos alxébricos (type), operadores (op ::) e sinaturas de funcións (fn ::) definidos en src/main/ridgun/lib/regex.rg (4 tipos, 0 operadores e 70 funcións):
Tipos alxébricos e rexistros (type) de regex:
type RegexMatch = matched: Bool, match_start: Int, match_end: Int, text: String
type ReNode = ReEmpty | ReChar Int | ReAny | ReClass Bool [Int] | ReShort Int | ReBol | ReEol | ReStar ReNode | RePlus ReNode | ReOpt ReNode | ReSeq ReNode ReNode | ReAlt ReNode ReNode
type ReParseRes = ReParseRes ReNode Int
type NfaInst = InstChar Int Int | InstAny Int | InstClass Bool [Int] Int | InstShort Int Int | InstBol Int | InstEol Int | InstSplit Int Int | InstJump Int | InstMatch| # | Función / Sinatura (fn ::) | Tipo de Retorno |
|---|---|---|
1 | fn :: re is digit Int | Bool |
2 | fn :: re is word Int | Bool |
3 | fn :: re is space Int | Bool |
4 | fn :: re match short Int Int | Bool |
5 | fn :: re in ranges Int [Int] | Bool |
6 | fn :: re escape char Int | ReNode |
7 | fn :: re class char String Int Int | (Int Int) |
8 | fn :: re fst int (Int Int) | Int |
9 | fn :: re snd int (Int Int) | Int |
10 | fn :: re parse class items String Int Int [Int] | ([Int] Int) |
11 | fn :: re parse class item step String Int Int [Int] | ([Int] Int) |
12 | fn :: re parse class range check String Int Int Int [Int] | ([Int] Int) |
13 | fn :: re parse class range hi String Int Int Int [Int] | ([Int] Int) |
14 | fn :: re fst ranges ([Int] Int) | [Int] |
15 | fn :: re snd pos ([Int] Int) | Int |
16 | fn :: re parse class String Int Int | ReParseRes |
17 | fn :: re finish class Bool ([Int] Int) | ReParseRes |
18 | fn :: re res node ReParseRes | ReNode |
19 | fn :: re res pos ReParseRes | Int |
20 | fn :: re parse group String Int Int | ReParseRes |
21 | fn :: re close group ReNode String Int Int | ReParseRes |
22 | fn :: re parse atom String Int Int | ReParseRes |
23 | fn :: re parse postfix ReNode String Int Int | ReParseRes |
24 | fn :: re parse factor String Int Int | ReParseRes |
25 | fn :: re is seq stop Int | Bool |
26 | fn :: re parse seq loop ReNode String Int Int | ReParseRes |
27 | fn :: re parse seq step ReNode String Int Int | ReParseRes |
28 | fn :: re parse seq String Int Int | ReParseRes |
29 | fn :: re parse seq first String Int Int | ReParseRes |
30 | fn :: re parse alt loop ReNode String Int Int | ReParseRes |
31 | fn :: re parse alt branch ReNode String Int Int | ReParseRes |
32 | fn :: re parse alt String Int Int | ReParseRes |
33 | fn :: nfa len [NfaInst] | Int |
34 | fn :: re compile seq ReNode ReNode Int | [NfaInst] |
35 | fn :: re compile opt ReNode Int | [NfaInst] |
36 | fn :: re compile star ReNode Int | [NfaInst] |
37 | fn :: re compile plus ReNode Int | [NfaInst] |
38 | fn :: re compile alt ReNode ReNode Int | [NfaInst] |
39 | fn :: re compile node ReNode Int | [NfaInst] |
40 | fn :: re compile String | [NfaInst] |
41 | fn :: nfa inst at [NfaInst] Int | NfaInst |
42 | fn :: nfa set has [Int] Int | Bool |
43 | fn :: nfa closure [NfaInst] [Int] Int Int [Int] | [Int] |
44 | fn :: nfa closure inst [NfaInst] Int [Int] Int Int [Int] NfaInst | [Int] |
45 | fn :: nfa step one NfaInst Int | [Int] |
46 | fn :: nfa step [NfaInst] [Int] Int | [Int] |
47 | fn :: nfa is match inst NfaInst | Bool |
48 | fn :: nfa has match [NfaInst] [Int] | Bool |
49 | fn :: nfa update last [NfaInst] [Int] Int Int | Int |
50 | fn :: nfa sim loop [NfaInst] String Int Int [Int] Int | Int |
51 | fn :: nfa sim step [NfaInst] String Int Int [Int] Int | Int |
52 | fn :: nfa longest from [NfaInst] String Int Int | Int |
53 | fn :: nfa full loop [NfaInst] String Int Int [Int] | Bool |
54 | fn :: nfa full step [NfaInst] String Int Int [Int] | Bool |
55 | fn :: regex match String String | Bool |
56 | fn :: nfa find from [NfaInst] String Int Int | RegexMatch |
57 | fn :: nfa find check [NfaInst] String Int Int Int | RegexMatch |
58 | fn :: regex find String String | RegexMatch |
59 | fn :: regex is match String String | Bool |
60 | fn :: nfa find all loop [NfaInst] String Int Int [RegexMatch] | [RegexMatch] |
61 | fn :: nfa find all step [NfaInst] String Int Int [RegexMatch] Int | [RegexMatch] |
62 | fn :: regex find all String String | [RegexMatch] |
63 | fn :: regex replace String String String | String |
64 | fn :: re apply replace RegexMatch String String | String |
65 | fn :: nfa replace all loop [NfaInst] String String Int Int String | String |
66 | fn :: nfa replace all step [NfaInst] String String Int Int String Int | String |
67 | fn :: regex replace all String String String | String |
68 | fn :: nfa split loop [NfaInst] String Int Int Int [String] | [String] |
69 | fn :: nfa split step [NfaInst] String Int Int Int [String] Int | [String] |
70 | fn :: regex split String String | [String] |
19.3. Explorando regex a fondo: Exemplos paso a paso de cada funcionalidade
Non abonda con ver a táboa de sinaturas: imos explorar cada unha das funcionalidades da lib regex mediante exemplos progresivos e executables en Ridgun. Comezaremos polas dúas receitas tabulares de uso cotián e despois percorreremos en detalle todos os escenarios funcionais, transformacións e casos límite verificados en src/test/ridgun/test regex.rg.
19.3.1. Exemplo 1: Fluxo principal en estilo tabular con regex
Observa como en Ridgun os signos = e os pasos de transformación con regex quedan aliñados coma unha táboa limpa, sen variables mutables innecesarias nin efectos laterais ocultos:
import regex
fn :: extraer codigos postales String => [String]
extraer codigos postales texto =
regex find all "\d+" texto19.3.2. Exemplo 2: Composición segura e manexo de casos de bordo
Toda función da lib regex está deseñada para compoñerse con gardas booleanas | e co resto das 32 libs de ridgun-libs:
import regex
fn :: censurar telefonos String => Bool String
censurar telefonos comentario =
regex is match "\d+-\d+" comentario -> tiene
regex replace all "\d+-\d+" comentario "[TELEFONO]" -> limpio
(tiene, limpio)19.3.3. Exemplo 3: Áncoras (^, $), cuantificadores (*, +, ?), alternancia (|), grupos (...), clases [a-z0-9] e atallos (\d, \w, \s)
Neste exemplo práctico exploramos de forma exhaustiva como se comporta regex neste bloque funcional, incluíndo entradas estándar, combinacións de parámetros e valores fronteira:
fn :: test regex operators and classes => ()
test regex operators and classes =
assert true (regex match "" "") "AC1: empty pattern matches empty string"
assert false (regex match "" "nonempty") "AC1: empty pattern rejects non-empty on full match"
assert true (regex match 'a(b|c)+d?e*' "abcbdeee") "AC1: alternation group plus opt star"
assert true (regex match 'a(b|c)+d?e*' "ac") "AC1: opt and star match zero occurrences"
assert false (regex match 'a(b|c)+d?e*' "ade") "AC1: plus requires at least one"
assert true (regex match '(foo|bar|baz)+' "barfoobazbar") "AC1: multi-branch alternation with plus"
assert false (regex match '(foo|bar|baz)+' "barquxfoo") "AC1: multi-branch alternation rejects unknown"
assert true (regex match '[a-zA-Z_][a-zA-Z0-9_]*' "_valid_Identifier_99") "AC1: identifier character class"
assert false (regex match '[a-zA-Z_][a-zA-Z0-9_]*' "9invalid") "AC1: identifier rejects leading digit"
assert true (regex match '[^0-9]+' "hello_world") "AC1: negated char class"
assert false (regex match '[^0-9]+' "hello42") "AC1: negated char class rejects digits"
assert true (regex match '\w+\s+\d+' "agent 007") "AC1: shorthand escapes \\w \\s \\d"
assert true (regex match '\D+\S+' "abc_123") "AC1: negated shorthand escapes \\D \\S"
assert true (regex match 'v\d+\.\d+\.\d+' "v0.9.16") "AC1: escaped dot literal"
assert false (regex match 'v\d+\.\d+\.\d+' "v0X9Y16") "AC1: escaped dot rejects non-dot"
assert true (regex is match '^hello' "hello world") "AC1: bol anchor matches start"
assert false (regex is match '^world' "hello world") "AC1: bol anchor rejects middle"
assert true (regex is match 'world$' "hello world") "AC1: eol anchor matches end"
assert false (regex is match 'hello$' "hello world") "AC1: eol anchor rejects prefix"
assert true (regex is match '^exact$' "exact") "AC1: anchored ^exact$ matches full string"
assert false (regex is match '^exact$' "not exact") "AC1: anchored ^exact$ rejects extra chars"
-- Russ Cox pathological backtracking benchmarks (exponential in backtracking engines, O(N*M) in Thompson NFA)
assert false (regex match '(a+)+b' "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaac") "AC1: Thompson NFA immune to (a+)+b ReDoS"
assert false (regex match '(a|aa)+b' "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaac") "AC1: Thompson NFA immune to (a|aa)+b ReDoS"
assert true (regex match 'a?a?a?a?a?a?a?a?aaaaaaaa' "aaaaaaaa") "AC1: Russ Cox a?^n a^n vector"
()19.3.4. Exemplo 4: Extracción de coincidencias (regex find, regex find all), substitución (regex replace, regex replace all) e división (regex split)
Neste exemplo práctico exploramos de forma exhaustiva como se comporta regex neste bloque funcional, incluíndo entradas estándar, combinacións de parámetros e valores fronteira:
fn :: test regex find replace split => ()
test regex find replace split =
m1 = regex find '\d+' "item #42 and #99"
assert true (matched m1) "AC2: find matched"
assert int equals (match_start m1) 6 "AC2: find start"
assert int equals (match_end m1) 8 "AC2: find end"
assert str eq (text m1) "42" "AC2: find text"
m_none = regex find '\d+' "no digits here"
assert false (matched m_none) "AC2: find returns matched=False when absent"
all_m = regex find all '[a-z]+=\d+' "id=10, port=8080, ttl=60"
assert int equals (re match count all_m) 3 "AC2: find all key=val count"
assert str eq (text (re match at all_m 0)) "id=10" "AC2: find all first match"
assert str eq (text (re match at all_m 1)) "port=8080" "AC2: find all second match"
assert str eq (text (re match at all_m 2)) "ttl=60" "AC2: find all third match"
r1 = regex replace '\d+' "X" "v1.2.3"
assert str eq r1 "vX.2.3" "AC3: replace first"
r_no = regex replace '\d+' "X" "abc"
assert str eq r_no "abc" "AC3: replace with no match returns original"
r2 = regex replace all '\d+' "X" "v1.22.333"
assert str eq r2 "vX.X.X" "AC3: replace all"
parts = regex split '\s*[,;]\s*' "alpha, beta ; gamma,delta"
assert int equals (re str count parts) 4 "AC3: split count"
assert str eq (re str at parts 0) "alpha" "AC3: split[0]"
assert str eq (re str at parts 1) "beta" "AC3: split[1]"
assert str eq (re str at parts 2) "gamma" "AC3: split[2]"
assert str eq (re str at parts 3) "delta" "AC3: split[3]"
()19.3.5. Exemplo 5: Validador de identificadores e anonimizador de trazas en tempo lineal $O(N \cdot M)$ con Thompson NFA (regex is match, regex replace all, regex split)
Neste exemplo práctico exploramos de forma exhaustiva como se comporta regex neste bloque funcional, incluíndo entradas estándar, combinacións de parámetros e valores fronteira:
import regex
fn :: limpiar traza y validar id (usuario_id : String) (linea_log : String) => (Bool, String, [String])
limpiar traza y validar id usuario_id linea_log =
id_valido = regex is match "^usr_[a-z0-9]+$" usuario_id
sin_ips = regex replace all "\d+\.\d+\.\d+\.\d+" linea_log "[IP-REDACTADA]"
tokens = regex split "\s+" sin_ips
(id_valido, sin_ips, tokens)19.4. Baixo o capó: como está construída regex en Ridgun puro (src/main/ridgun/lib/regex.rg)
Unha das maiores vantaxes de ridgun-libs é que non hai caixas negras en C. Podes abrir src/main/ridgun/lib/regex.rg e ler exactamente como está implementada cada operación usando pattern matching, árbores de gardas | / |. e recursión de cola (TCO). Vexamos as pezas clave da súa implementación real:
19.4.1. Implementación interna: Character Class & Shorthand Helpers
Fíxate en como regex.rg estrutura as sinaturas fn :: ... => ... primeiro e resolve cada caso mediante ecuacións aliñadas e chamadas de cola:
module :: regex
fn :: re is digit Int => Bool
re is digit c = c >= 48 and c <= 57
fn :: re is word Int => Bool
re is word c = (c >= 48 and c <= 57) or (c >= 65 and c <= 90) or (c >= 97 and c <= 122) or c == 95
fn :: re is space Int => Bool
re is space c = c == 32 or c == 9 or c == 10 or c == 13 or c == 11 or c == 12
fn :: re match short Int Int => Bool
re match short 100 c = re is digit c
re match short 68 c = not (re is digit c)
re match short 119 c = re is word c
re match short 87 c = not (re is word c)
re match short 115 c = re is space c
re match short 83 c = not (re is space c)
re match short _ _ = False
fn :: re in ranges Int [Int] => Bool
re in ranges _ [] = False
re in ranges _ (_:[]) = False
re in ranges c (lo:hi:rs) =
| c >= lo and c <= hi = True
| otherwise = re in ranges c rs19.4.2. Implementación interna: Thompson NFA Compiler (ReNode -> [NfaInst])
Fíxate en como regex.rg estrutura as sinaturas fn :: ... => ... primeiro e resolve cada caso mediante ecuacións aliñadas e chamadas de cola:
fn :: nfa len [NfaInst] => Int
nfa len [] = 0
nfa len (_:rest) = 1 + (nfa len rest)
fn :: re compile seq ReNode ReNode Int => [NfaInst]
re compile seq a b start_id =
insts_a = re compile node a start_id
mid_id = start_id + (nfa len insts_a)
insts_b = re compile node b mid_id
insts_a :: insts_b
fn :: re compile opt ReNode Int => [NfaInst]
re compile opt a start_id =
body = re compile node a (start_id + 1)
end_id = start_id + 1 + (nfa len body)
[InstSplit (start_id + 1) end_id] :: body
fn :: re compile star ReNode Int => [NfaInst]
re compile star a start_id =
body = re compile node a (start_id + 1)
end_id = start_id + 2 + (nfa len body)
([InstSplit (start_id + 1) end_id] :: body) :: [InstJump start_id]
fn :: re compile plus ReNode Int => [NfaInst]
re compile plus a start_id =
body = re compile node a start_id
split_id = start_id + (nfa len body)
body :: [InstSplit start_id (split_id + 1)]
fn :: re compile alt ReNode ReNode Int => [NfaInst]
re compile alt a b start_id =
body_a = re compile node a (start_id + 1)
jump_id = start_id + 1 + (nfa len body_a)
start_b = jump_id + 1
body_b = re compile node b start_b
end_id = start_b + (nfa len body_b)
(([InstSplit (start_id + 1) start_b] :: body_a) :: [InstJump end_id]) :: body_b
fn :: re compile node ReNode Int => [NfaInst]
re compile node ReEmpty _ = []
re compile node (ReChar c) start_id = [InstChar c (start_id + 1)]
re compile node ReAny start_id = [InstAny (start_id + 1)]
re compile node (ReClass neg rngs) start_id = [InstClass neg rngs (start_id + 1)]
re compile node (ReShort k) start_id = [InstShort k (start_id + 1)]
re compile node ReBol start_id = [InstBol (start_id + 1)]
re compile node ReEol start_id = [InstEol (start_id + 1)]
re compile node (ReOpt a) start_id = re compile opt a start_id
re compile node (ReStar a) start_id = re compile star a start_id
re compile node (RePlus a) start_id = re compile plus a start_id
re compile node (ReSeq a b) start_id = re compile seq a b start_id
re compile node (ReAlt a b) start_id = re compile alt a b start_id
fn :: re compile String => [NfaInst]
re compile pat =
re parse alt pat 0 (str len pat) -> parsed
(re compile node (re res node parsed) 0) :: [InstMatch]19.4.3. Implementación interna: Linear-Time Thompson NFA State-Set Simulation
Fíxate en como regex.rg estrutura as sinaturas fn :: ... => ... primeiro e resolve cada caso mediante ecuacións aliñadas e chamadas de cola:
fn :: nfa inst at [NfaInst] Int => NfaInst
nfa inst at [] _ = InstMatch
nfa inst at (i:_) 0 = i
nfa inst at (_:rest) idx = nfa inst at rest (idx - 1)
fn :: nfa set has [Int] Int => Bool
nfa set has [] _ = False
nfa set has (x:xs) v =
| x == v = True
| otherwise = nfa set has xs v
fn :: nfa closure [NfaInst] [Int] Int Int [Int] => [Int]
nfa closure _ [] _ _ visited = visited
nfa closure prog (s:ss) pos len visited =
| nfa set has visited s = nfa closure prog ss pos len visited
| otherwise = nfa closure inst prog s ss pos len (visited :: [s]) (nfa inst at prog s)
fn :: nfa closure inst [NfaInst] Int [Int] Int Int [Int] NfaInst => [Int]
nfa closure inst prog _ ss pos len vis (InstJump out) = nfa closure prog ([out] :: ss) pos len vis
nfa closure inst prog _ ss pos len vis (InstSplit o1 o2) = nfa closure prog ([o1, o2] :: ss) pos len vis
nfa closure inst prog _ ss pos len vis (InstBol out) =
| pos == 0 = nfa closure prog ([out] :: ss) pos len vis
| otherwise = nfa closure prog ss pos len vis
nfa closure inst prog _ ss pos len vis (InstEol out) =
| pos == len = nfa closure prog ([out] :: ss) pos len vis
| otherwise = nfa closure prog ss pos len vis
nfa closure inst prog _ ss pos len vis _ = nfa closure prog ss pos len vis
fn :: nfa step one NfaInst Int => [Int]
nfa step one (InstChar expected out) c =
| c == expected = [out]
| otherwise = []
nfa step one (InstAny out) c =
| c != 10 = [out]
| otherwise = []
nfa step one (InstClass neg rngs out) c =
| (re in ranges c rngs) != neg = [out]
| otherwise = []
nfa step one (InstShort kind out) c =
| re match short kind c = [out]
| otherwise = []
nfa step one _ _ = []
fn :: nfa step [NfaInst] [Int] Int => [Int]
nfa step _ [] _ = []
nfa step prog (s:ss) c = (nfa step one (nfa inst at prog s) c) :: (nfa step prog ss c)
fn :: nfa is match inst NfaInst => Bool
nfa is match inst InstMatch = True
nfa is match inst _ = False
fn :: nfa has match [NfaInst] [Int] => Bool
nfa has match _ [] = False
nfa has match prog (s:ss) =
| nfa is match inst (nfa inst at prog s) = True
| otherwise = nfa has match prog ss
fn :: nfa update last [NfaInst] [Int] Int Int => Int
nfa update last prog active cand cur =
| nfa has match prog active = cand
| otherwise = cur
fn :: nfa sim loop [NfaInst] String Int Int [Int] Int => Int
nfa sim loop _ _ _ _ [] last_m = last_m
nfa sim loop prog input pos len active last_m =
| pos >= len = last_m
| otherwise = nfa sim step prog input pos len active last_m
fn :: nfa sim step [NfaInst] String Int Int [Int] Int => Int
nfa sim step prog input pos len active last_m =
str char at input pos -> c
nfa closure prog (nfa step prog active c) (pos + 1) len [] -> next_act
nfa update last prog next_act (pos + 1) last_m -> next_last
nfa sim loop prog input (pos + 1) len next_act next_last
fn :: nfa longest from [NfaInst] String Int Int => Int
nfa longest from prog input pos len =
nfa closure prog [0] pos len [] -> init_act
nfa update last prog init_act pos (0 - 1) -> init_last
nfa sim loop prog input pos len init_act init_last
fn :: nfa full loop [NfaInst] String Int Int [Int] => Bool
nfa full loop _ _ _ _ [] = False
nfa full loop prog input pos len active =
| pos >= len = nfa has match prog active
| otherwise = nfa full step prog input pos len active
fn :: nfa full step [NfaInst] String Int Int [Int] => Bool
nfa full step prog input pos len active =
str char at input pos -> c
nfa closure prog (nfa step prog active c) (pos + 1) len [] -> next_act
nfa full loop prog input (pos + 1) len next_act19.4.4. Implementación interna: Public Regex API (API-REGEX-001)
Fíxate en como regex.rg estrutura as sinaturas fn :: ... => ... primeiro e resolve cada caso mediante ecuacións aliñadas e chamadas de cola:
fn :: regex match String String => Bool
regex match pat input =
pat re compile -> prog
input str len -> len
nfa closure prog [0] 0 len [] -> init_act
nfa full loop prog input 0 len init_act
fn :: nfa find from [NfaInst] String Int Int => RegexMatch
nfa find from prog input pos len =
| pos > len = RegexMatch False (0 - 1) (0 - 1) ""
| otherwise = nfa find check prog input pos len (nfa longest from prog input pos len)
fn :: nfa find check [NfaInst] String Int Int Int => RegexMatch
nfa find check prog input pos len end_pos =
| end_pos >= pos = RegexMatch True pos end_pos (str slice input pos end_pos)
| otherwise = nfa find from prog input (pos + 1) len
fn :: regex find String String => RegexMatch
regex find pat input =
pat re compile -> prog
nfa find from prog input 0 (str len input)
fn :: regex is match String String => Bool
regex is match pat input = regex find pat input -> matched
fn :: nfa find all loop [NfaInst] String Int Int [RegexMatch] => [RegexMatch]
nfa find all loop prog input pos len acc =
| pos > len = acc
| otherwise = nfa find all step prog input pos len acc (nfa longest from prog input pos len)
fn :: nfa find all step [NfaInst] String Int Int [RegexMatch] Int => [RegexMatch]
nfa find all step prog input pos len acc end_pos =
| end_pos > pos = nfa find all loop prog input end_pos len (acc :: [RegexMatch True pos end_pos (str slice input pos end_pos)])
| end_pos == pos = nfa find all loop prog input (pos + 1) len (acc :: [RegexMatch True pos pos ""])
| otherwise = nfa find all loop prog input (pos + 1) len acc
fn :: regex find all String String => [RegexMatch]
regex find all pat input =
pat re compile -> prog
nfa find all loop prog input 0 (str len input) []
fn :: regex replace String String String => String
regex replace pat repl input =
regex find pat input -> m
re apply replace m repl input
fn :: re apply replace RegexMatch String String => String
re apply replace m repl input =
| not (matched m) = input
| otherwise = (str slice input 0 (match_start m)) + repl + (str slice input (match_end m) (str len input))
fn :: nfa replace all loop [NfaInst] String String Int Int String => String
nfa replace all loop prog repl input pos len acc =
| pos >= len = acc
| otherwise = nfa replace all step prog repl input pos len acc (nfa longest from prog input pos len)
fn :: nfa replace all step [NfaInst] String String Int Int String Int => String
nfa replace all step prog repl input pos len acc end_pos =
| end_pos > pos = nfa replace all loop prog repl input end_pos len (acc + repl)
| otherwise = nfa replace all loop prog repl input (pos + 1) len (acc + (str slice input pos (pos + 1)))
fn :: regex replace all String String String => String
regex replace all pat repl input =
pat re compile -> prog
nfa replace all loop prog repl input 0 (str len input) ""
fn :: nfa split loop [NfaInst] String Int Int Int [String] => [String]
nfa split loop prog input pos len last_s acc =
| pos >= len = acc :: [str slice input last_s len]
| otherwise = nfa split step prog input pos len last_s acc (nfa longest from prog input pos len)
fn :: nfa split step [NfaInst] String Int Int Int [String] Int => [String]
nfa split step prog input pos len last_s acc end_pos =
| end_pos > pos = nfa split loop prog input end_pos len end_pos (acc :: [str slice input last_s pos])
| otherwise = nfa split loop prog input (pos + 1) len last_s acc
fn :: regex split String String => [String]
regex split pat input =
pat re compile -> prog
nfa split loop prog input 0 (str len input) 0 []19.5. Garantías algorítmicas, memoria RMM1/RMM2 e as 5 Regras de Ouro de regex
- Garantía algorítmica e de seguridade: Simulación de conxunto de estados NFA sen recursión descontrolada de pila e tempo $O(N \cdot M)$ garantido mesmo ante padróns patolóxicos
(a+)+b. - Complexidade de pila $O(1)$ con TCO: Todos os bucles recursivos en
src/main/ridgun/lib/regex.rgestán en posición de cola, polo queridguncos compila a saltos nativos sen crecemento de pila. - Memoria determinista (
RMM1/RMM2): Cero pausas de colector de lixo; todas as estruturas intermedias libéranse de forma determinista ao saír do ámbito. - Verificación continua: Probada exhaustivamente con
stable checke a suite automatizadasrc/test/ridgun/test regex.rg.
As 5 Regras de Ouro ao programar con regex
- Declara
import regexao inicio do ficheiro e aproveita a equivalencia entre espazos e guións baixos para que o teu código se lea coma prosa. - Aliña as túas tubaxes de datos con
=: encadea as chamadas aregexen pasos con nome propio e deixa questable formataliñe as columnas. - Aproveita as funcións totais de
regexnas túas gardas|: comproba os valores de retorno ou desenvolve os ADTs con pattern matching en vez de asumir que a entrada externa sempre é válida. - Evita copiar grandes estruturas se só necesitas consultar un campo: lembra que en
RMM2os argumentos de entrada non incrementan nin decrementan contadores (+0/-0). - Combina
regexcontest(import test): escribe sempre asercións conassert equalsouassert truepara fixar os invariantes do teu dominio.
No Capítulo 20 pasaremos a explorar en profundidade a lib glob (A lib glob — Padróns de Comodíns (*, ?, [a-z]) e Filtrado de Listas).