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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,227 @@ | ||
| package libvore | ||
|
|
||
| import ( | ||
| "strconv" | ||
| ) | ||
|
|
||
| // This is mostly built off of the ECMAScript spec for regular expressions | ||
| // https://262.ecma-international.org/13.0/#sec-patterns | ||
| // this was mostly because it was the easiest to find the grammar | ||
|
|
||
| /* | ||
| PATTERN :: DISJUNCTION | ||
| DISJUNCTION :: ALTERNATIVE | ||
| :: ALTERNATIVE | DISJUNCTION | ||
| ALTERNATIVE :: [empty] | ||
| :: ALTERNATIVE TERM | ||
| TERM :: ASSERTION | ||
| :: ATOM | ||
| :: ATOM QUANTIFIER | ||
| ASSERTION :: ^ | ||
| :: $ | ||
| :: \ b | ||
| :: \ B | ||
| :: ( ? = DISJUNCTION ) | ||
| :: ( ? ! DISJUNCTION ) | ||
| :: ( ? < = DISJUNCTION ) | ||
| :: ( ? < ! DISJUNCTION ) | ||
| QUANTIFIER :: QUANTIFIERPREFIX | ||
| :: QUANTIFIERPREFIX ? | ||
| QUANTIFIERPREFIX :: * | ||
| :: + | ||
| :: ? | ||
| :: { DECIMALDIGITS } | ||
| :: { DECIMALDIGITS , } | ||
| :: { DECIMALDIGITS , DECIMALDIGITS } | ||
| ATOM :: PATTERNCHARACTER | ||
| :: . | ||
| :: \ ATOMESCAPE | ||
| :: CHARACTERCLASS | ||
| :: ( GROUPSPECIFIER DISJUNCTION ) | ||
| :: ( ? : DISJUNCTION ) | ||
| SYNTAXCHARACTER :: one of ^ $ \ . * + ? ( ) [ ] { } | ||
| PATTERNCHARACTER :: any single character except for SYNTAXCHARACTER | ||
| ATOMESCAPE :: unimplemented | ||
| CHARACTERCLASS :: unimplemented | ||
| GROUPSPECIFIER :: [empty] | ||
| :: ? GROUPNAME | ||
| GROUPNAME :: < IDENTIFIER > -- will break ECMAScript standard here and just do the same style identifiers in vore | ||
| */ | ||
|
|
||
| func parse_regexp(tokens []*Token, token_index int) (AstExpression, int, error) { | ||
| regexp_token := tokens[token_index] | ||
| regexp := regexp_token.Lexeme | ||
|
|
||
| index := 0 | ||
| results := []AstExpression{} | ||
| for index < len(regexp) { | ||
| exp, next_index, err := parse_regexp_pattern(regexp_token, regexp, index) | ||
| if err != nil { | ||
| return nil, next_index, err | ||
| } | ||
| results = append(results, exp) | ||
| index = next_index | ||
| } | ||
|
|
||
| s := &AstPrimary{ | ||
| &AstSubExpr{results}, | ||
| } | ||
|
|
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| return s, token_index + 1, nil | ||
| } | ||
|
|
||
| func parse_regexp_pattern(regexp_token *Token, regexp string, index int) (AstExpression, int, error) { | ||
|
|
||
| start, next_index, err := parse_regexp_literal(regexp_token, regexp, index) | ||
| if err != nil { | ||
| return nil, next_index, err | ||
| } | ||
|
|
||
| if next_index >= len(regexp) { | ||
| return &AstPrimary{start}, next_index, nil | ||
| } | ||
|
|
||
| op := regexp[next_index] | ||
| if op == '*' { | ||
| fewest := next_index+1 < len(regexp) && regexp[next_index+1] == '?' | ||
| exp := &AstLoop{0, -1, fewest, &AstPrimary{start}, ""} | ||
| if fewest { | ||
| return exp, next_index + 2, nil | ||
| } else { | ||
| return exp, next_index + 1, nil | ||
| } | ||
| } else if op == '+' { | ||
| fewest := next_index+1 < len(regexp) && regexp[next_index+1] == '?' | ||
| exp := &AstLoop{1, -1, fewest, &AstPrimary{start}, ""} | ||
| if fewest { | ||
| return exp, next_index + 2, nil | ||
| } else { | ||
| return exp, next_index + 1, nil | ||
| } | ||
| } else if op == '?' { | ||
| fewest := next_index+1 < len(regexp) && regexp[next_index+1] == '?' | ||
| exp := &AstLoop{0, 1, fewest, &AstPrimary{start}, ""} | ||
| if fewest { | ||
| return exp, next_index + 2, nil | ||
| } else { | ||
| return exp, next_index + 1, nil | ||
| } | ||
| } else if op == '{' { | ||
| from, idx, err := parse_regexp_number(regexp_token, regexp, next_index+1) | ||
| if err != nil { | ||
| return nil, idx, err | ||
| } | ||
| comma_or_brace := regexp[idx] | ||
| var end_idx int | ||
| var exp *AstLoop | ||
| if comma_or_brace == ',' { | ||
| if regexp[idx+1] == '}' { | ||
| exp = &AstLoop{from, -1, false, &AstPrimary{start}, ""} | ||
| end_idx = idx + 1 | ||
| } else { | ||
| to, idx2, err := parse_regexp_number(regexp_token, regexp, idx+1) | ||
| if err != nil { | ||
| return nil, idx, err | ||
| } | ||
| brace := regexp[idx2] | ||
| if brace != '}' { | ||
| return nil, idx2, NewParseError(*regexp_token, "Unexpected character. Expected '}'") | ||
| } | ||
|
|
||
| exp = &AstLoop{from, to, false, &AstPrimary{start}, ""} | ||
| end_idx = idx2 + 1 | ||
| } | ||
| } else if comma_or_brace == '}' { | ||
| exp = &AstLoop{from, from, false, &AstPrimary{start}, ""} | ||
| end_idx = idx + 1 | ||
| } | ||
| exp.fewest = end_idx+1 < len(regexp) && regexp[end_idx+1] == '?' | ||
| if exp.fewest { | ||
| return exp, end_idx + 2, nil | ||
| } else { | ||
| return exp, end_idx + 1, nil | ||
| } | ||
| } else if op == '|' { | ||
| end, idx, err := parse_regexp_pattern(regexp_token, regexp, next_index+1) | ||
| return &AstBranch{start, end}, idx, err | ||
| } | ||
|
|
||
| return &AstPrimary{start}, next_index, nil | ||
| } | ||
|
|
||
| func parse_regexp_number(regexp_token *Token, regexp string, index int) (int, int, error) { | ||
| c := regexp[index] | ||
| result := "" | ||
| idx := index | ||
| for c >= '0' && c <= '9' { | ||
| result += string(c) | ||
| idx += 1 | ||
| c = regexp[idx] | ||
| } | ||
| if result == "" { | ||
| return -1, index, NewParseError(*regexp_token, "Unexpected Token. Expected number") | ||
| } | ||
| value, err := strconv.Atoi(result) | ||
| if err != nil { | ||
| return value, idx, NewParseError(*regexp_token, "Error converting string to number") | ||
| } | ||
| return value, idx, nil | ||
|
|
||
| } | ||
|
|
||
| func parse_regexp_literal(regexp_token *Token, regexp string, index int) (AstLiteral, int, error) { | ||
| c := regexp[index] | ||
| var start AstLiteral | ||
| next_index := index | ||
| if c == '^' { | ||
| start = &AstCharacterClass{false, ClassLineStart} | ||
| next_index += 1 | ||
| } else if c == '$' { | ||
| start = &AstCharacterClass{false, ClassLineEnd} | ||
| next_index += 1 | ||
| } else if c == '\\' { | ||
| exp, idx, err := parse_regexp_escape_characters(regexp_token, regexp, index+1) | ||
| if err != nil { | ||
| return nil, index, err | ||
| } | ||
| start = exp | ||
| next_index = idx | ||
| } else if c == '(' { | ||
| exp, idx, err := parse_regexp_groups(regexp_token, regexp, index+1) | ||
| if err != nil { | ||
| return nil, index, err | ||
| } | ||
| start = exp | ||
| next_index = idx | ||
| } else if c == '.' { | ||
| start = &AstString{true, "\n", false} | ||
| next_index += 1 | ||
| } else { | ||
| start = &AstString{false, string(c), false} | ||
| next_index += 1 | ||
| } | ||
| return start, next_index, nil | ||
| } | ||
|
|
||
| func parse_regexp_escape_characters(regexp_token *Token, regexp string, index int) (AstLiteral, int, error) { | ||
| return nil, index, nil | ||
| } | ||
|
|
||
| func parse_regexp_groups(regexp_token *Token, regexp string, index int) (AstLiteral, int, error) { | ||
| return nil, index, nil | ||
| } |
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