Add `core:text/regex`

1 files changed, 580 insertions, 0 deletions

diff --git a/core/text/regex/parser/parser.odin b/core/text/regex/parser/parser.odin
new file mode 100644
index 000000000..1958ee399
--- /dev/null
+++ b/core/text/regex/parser/parser.odin
@@ -0,0 +1,580 @@
+package regex_parser
+
+import "base:intrinsics"
+import "core:strconv"
+import "core:strings"
+import "core:text/regex/common"
+import "core:text/regex/tokenizer"
+import "core:unicode"
+import "core:unicode/utf8"
+
+Token      :: tokenizer.Token
+Token_Kind :: tokenizer.Token_Kind
+Tokenizer  :: tokenizer.Tokenizer
+
+Rune_Class_Range :: struct {
+	lower, upper: rune,
+}
+Rune_Class_Data :: struct {
+	runes: [dynamic]rune,
+	ranges: [dynamic]Rune_Class_Range,
+}
+
+
+Node_Rune :: struct {
+	data: rune,
+}
+
+Node_Rune_Class :: struct {
+	negating: bool,
+	using data: Rune_Class_Data,
+}
+
+Node_Wildcard :: struct {}
+
+Node_Alternation :: struct {
+	left, right: Node,
+}
+
+Node_Concatenation :: struct {
+	nodes: [dynamic]Node,
+}
+
+Node_Repeat_Zero :: struct {
+	inner: Node,
+}
+Node_Repeat_Zero_Non_Greedy :: struct {
+	inner: Node,
+}
+Node_Repeat_One :: struct {
+	inner: Node,
+}
+Node_Repeat_One_Non_Greedy :: struct {
+	inner: Node,
+}
+
+Node_Repeat_N :: struct {
+	inner: Node,
+	lower, upper: int,
+}
+
+Node_Optional :: struct {
+	inner: Node,
+}
+Node_Optional_Non_Greedy :: struct {
+	inner: Node,
+}
+
+Node_Group :: struct {
+	inner: Node,
+	capture_id: int,
+	capture: bool,
+}
+
+Node_Anchor :: struct {
+	start: bool,
+}
+Node_Word_Boundary :: struct {
+	non_word: bool,
+}
+
+Node_Match_All_And_Escape :: struct {}
+
+Node :: union {
+	^Node_Rune,
+	^Node_Rune_Class,
+	^Node_Wildcard,
+	^Node_Concatenation,
+	^Node_Alternation,
+	^Node_Repeat_Zero,
+	^Node_Repeat_Zero_Non_Greedy,
+	^Node_Repeat_One,
+	^Node_Repeat_One_Non_Greedy,
+	^Node_Repeat_N,
+	^Node_Optional,
+	^Node_Optional_Non_Greedy,
+	^Node_Group,
+	^Node_Anchor,
+	^Node_Word_Boundary,
+
+	// Optimized nodes (not created by the Parser):
+	^Node_Match_All_And_Escape,
+}
+
+
+left_binding_power :: proc(kind: Token_Kind) -> int {
+	#partial switch kind {
+	case .Alternate:                return 1
+	case .Concatenate:              return 2
+	case .Repeat_Zero, .Repeat_One,
+	     .Repeat_Zero_Non_Greedy, .Repeat_One_Non_Greedy,
+	     .Repeat_N:                 return 3
+	case .Optional,
+	     .Optional_Non_Greedy:      return 4
+	case .Open_Paren,
+	     .Open_Paren_Non_Capture:   return 9
+	}
+	return 0
+}
+
+
+Expected_Token :: struct {
+	pos: int,
+	kind: Token_Kind,
+}
+
+Invalid_Repetition :: struct {
+	pos: int,
+}
+
+Invalid_Token :: struct {
+	pos: int,
+	kind: Token_Kind,
+}
+
+Invalid_Unicode :: struct {
+	pos: int,
+}
+
+Too_Many_Capture_Groups :: struct {
+	pos: int,
+}
+
+Unexpected_EOF :: struct {
+	pos: int,
+}
+
+Error :: union {
+	Expected_Token,
+	Invalid_Repetition,
+	Invalid_Token,
+	Invalid_Unicode,
+	Too_Many_Capture_Groups,
+	Unexpected_EOF,
+}
+
+
+Parser :: struct {
+	flags: common.Flags,
+	t: Tokenizer,
+
+	cur_token: Token,
+
+	groups: int,
+}
+
+
+@require_results
+advance :: proc(p: ^Parser) -> Error {
+	p.cur_token = tokenizer.scan(&p.t)
+	if p.cur_token.kind == .Invalid {
+		return Invalid_Unicode { pos = 0 }
+	}
+	return nil
+}
+
+expect :: proc(p: ^Parser, kind: Token_Kind) -> (err: Error) {
+	if p.cur_token.kind == kind {
+		advance(p) or_return
+		return
+	}
+
+	return Expected_Token{
+		pos = p.t.offset,
+		kind = kind,
+	}
+}
+
+null_denotation :: proc(p: ^Parser, token: Token) -> (result: Node, err: Error) {
+	#partial switch token.kind {
+	case .Rune:
+		r: rune
+		for ru in token.text {
+			r = ru
+			break
+		}
+		assert(r != 0, "Parsed an empty Rune token.")
+
+		if .Case_Insensitive in p.flags {
+			lower := unicode.to_lower(r)
+			upper := unicode.to_upper(r)
+			if lower != upper {
+				node := new(Node_Rune_Class)
+				append(&node.runes, lower)
+				append(&node.runes, upper)
+				return node, nil
+			}
+		}
+
+		node := new(Node_Rune)
+		node ^= { r }
+		return node, nil
+
+	case .Rune_Class:
+		if len(token.text) == 0 {
+			return nil, nil
+		}
+
+		node := new(Node_Rune_Class)
+
+		for i := 0; i < len(token.text); /**/ {
+			r, size := utf8.decode_rune(token.text[i:])
+			if i == 0 && r == '^' {
+				node.negating = true
+				i += size
+				continue
+			}
+			i += size
+
+			assert(size > 0, "RegEx tokenizer passed an incomplete Rune_Class to the parser.")
+
+			if r == '\\' {
+				next_r, next_size := utf8.decode_rune(token.text[i:])
+				i += next_size
+				assert(next_size > 0, "RegEx tokenizer passed an incomplete Rune_Class to the parser.")
+
+				// @MetaCharacter
+				// NOTE: These must be kept in sync with the tokenizer.
+				switch next_r {
+				case 'f': append(&node.runes, '\f')
+				case 'n': append(&node.runes, '\n')
+				case 'r': append(&node.runes, '\r')
+				case 't': append(&node.runes, '\t')
+
+				case 'd':
+					append(&node.ranges, Rune_Class_Range{ '0', '9' })
+				case 's':
+					append(&node.runes, '\t')
+					append(&node.runes, '\n')
+					append(&node.runes, '\f')
+					append(&node.runes, '\r')
+					append(&node.runes, ' ')
+				case 'w':
+					append(&node.ranges, Rune_Class_Range{ '0', '9' })
+					append(&node.ranges, Rune_Class_Range{ 'A', 'Z' })
+					append(&node.runes, '_')
+					append(&node.ranges, Rune_Class_Range{ 'a', 'z' })
+				case 'D':
+					append(&node.ranges, Rune_Class_Range{        0,  '0' - 1  })
+					append(&node.ranges, Rune_Class_Range{  '9' + 1, max(rune) })
+				case 'S':
+					append(&node.ranges, Rune_Class_Range{        0, '\t' - 1  })
+					// \t and \n are adjacent.
+					append(&node.runes, '\x0b') // Vertical Tab
+					append(&node.ranges, Rune_Class_Range{ '\r' + 1,  ' ' - 1  })
+					append(&node.ranges, Rune_Class_Range{  ' ' + 1, max(rune) })
+				case 'W':
+					append(&node.ranges, Rune_Class_Range{        0,  '0' - 1  })
+					append(&node.ranges, Rune_Class_Range{  '9' + 1,  'A' - 1  })
+					append(&node.ranges, Rune_Class_Range{  'Z' + 1,  '_' - 1  })
+					append(&node.ranges, Rune_Class_Range{  '_' + 1,  'a' - 1  })
+					append(&node.ranges, Rune_Class_Range{  'z' + 1, max(rune) })
+				case:
+					append(&node.runes, next_r)
+				}
+				continue
+			}
+
+			if r == '-' && len(node.runes) > 0 {
+				next_r, next_size := utf8.decode_rune(token.text[i:])
+				if next_size > 0 {
+					last := pop(&node.runes)
+					i += next_size
+
+					append(&node.ranges, Rune_Class_Range{ last, next_r })
+					continue
+				}
+			}
+
+			append(&node.runes, r)
+		}
+
+		if .Case_Insensitive in p.flags {
+			length := len(node.runes)
+			#no_bounds_check for i := 0; i < length; i += 1 {
+				r := node.runes[i]
+				lower := unicode.to_lower(r)
+				upper := unicode.to_upper(r)
+
+				if lower != upper {
+					if lower != r {
+						append(&node.runes, lower)
+					} else {
+						append(&node.runes, upper)
+					}
+				}
+			}
+
+			length = len(node.ranges)
+			#no_bounds_check for i := 0; i < length; i += 1 {
+				range := &node.ranges[i]
+
+				min_lower := unicode.to_lower(range.lower)
+				max_lower := unicode.to_lower(range.upper)
+
+				min_upper := unicode.to_upper(range.lower)
+				max_upper := unicode.to_upper(range.upper)
+
+				if min_lower != min_upper && max_lower != max_upper {
+					range.lower = min_lower
+					range.upper = max_lower
+					append(&node.ranges, Rune_Class_Range{ min_upper, max_upper })
+				}
+			}
+		}
+
+		result = node
+
+	case .Wildcard:
+		node := new(Node_Wildcard)
+		result = node
+
+	case .Open_Paren:
+		// Because of the recursive nature of the token parser, we take the
+		// group number first instead of afterwards, in order to construct
+		// group matches from the outside in.
+		p.groups += 1
+		if p.groups == common.MAX_CAPTURE_GROUPS {
+			return nil, Too_Many_Capture_Groups{ pos = token.pos }
+		}
+		this_group := p.groups
+
+		node := new(Node_Group)
+		node.capture = true
+		node.capture_id = this_group
+
+		node.inner = parse_expression(p, 0) or_return
+		expect(p, .Close_Paren) or_return
+		result = node
+	case .Open_Paren_Non_Capture:
+		node := new(Node_Group)
+		node.inner = parse_expression(p, 0) or_return
+		expect(p, .Close_Paren) or_return
+		result = node
+	case .Close_Paren:
+		node := new(Node_Rune)
+		node ^= { ')' }
+		return node, nil
+		
+	case .Anchor_Start:
+		node := new(Node_Anchor)
+		node.start = true
+		result = node
+	case .Anchor_End:
+		node := new(Node_Anchor)
+		result = node
+	case .Word_Boundary:
+		node := new(Node_Word_Boundary)
+		result = node
+	case .Non_Word_Boundary:
+		node := new(Node_Word_Boundary)
+		node.non_word = true
+		result = node
+
+	case .Alternate:
+		// A unary alternation with a left-side empty path, i.e. `|a`.
+		right, right_err := parse_expression(p, left_binding_power(.Alternate))
+		#partial switch specific in right_err {
+		case Unexpected_EOF:
+			// This token is a NOP, i.e. `|`.
+			break
+		case nil:
+			break
+		case:
+			return nil, right_err
+		}
+
+		node := new(Node_Alternation)
+		node.right = right
+		result = node
+
+	case .EOF:
+		return nil, Unexpected_EOF{ pos = token.pos }
+
+	case:
+		return nil, Invalid_Token{ pos = token.pos, kind = token.kind }
+	}
+
+	return
+}
+
+left_denotation :: proc(p: ^Parser, token: Token, left: Node) -> (result: Node, err: Error) {
+	#partial switch token.kind {
+	case .Alternate:
+		if p.cur_token.kind == .Close_Paren {
+			// `(a|)`
+			// parse_expression will fail, so intervene here.
+			node := new(Node_Alternation)
+			node.left = left
+			return node, nil
+		}
+
+		right, right_err := parse_expression(p, left_binding_power(.Alternate))
+
+		#partial switch specific in right_err {
+		case nil:
+			break
+		case Unexpected_EOF:
+			// EOF is okay in an alternation; it's an edge case in the way of
+			// expressing an optional such as `a|`.
+			break
+		case:
+			return nil, right_err
+		}
+
+		node := new(Node_Alternation)
+		node.left = left
+		node.right = right
+		result = node
+
+	case .Concatenate:
+		right := parse_expression(p, left_binding_power(.Concatenate)) or_return
+
+		// There should be no need to check if right is Node_Concatenation, due
+		// to how the parsing direction works.
+		#partial switch specific in left {
+		case ^Node_Concatenation:
+			append(&specific.nodes, right)
+			result = specific
+		case:
+			node := new(Node_Concatenation)
+			append(&node.nodes, left)
+			append(&node.nodes, right)
+			result = node
+		}
+
+	case .Repeat_Zero:
+		node := new(Node_Repeat_Zero)
+		node.inner = left
+		result = node
+	case .Repeat_Zero_Non_Greedy:
+		node := new(Node_Repeat_Zero_Non_Greedy)
+		node.inner = left
+		result = node
+	case .Repeat_One:
+		node := new(Node_Repeat_One)
+		node.inner = left
+		result = node
+	case .Repeat_One_Non_Greedy:
+		node := new(Node_Repeat_One_Non_Greedy)
+		node.inner = left
+		result = node
+
+	case .Repeat_N:
+		node := new(Node_Repeat_N)
+		node.inner = left
+
+		comma := strings.index_byte(token.text, ',')
+
+		switch comma {
+		case -1: // {N}
+			exact, ok := strconv.parse_u64_of_base(token.text, base = 10)
+			if !ok {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+			if exact == 0 {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+
+			node.lower = cast(int)exact
+			node.upper = cast(int)exact
+
+		case 0: // {,M}
+			upper, ok := strconv.parse_u64_of_base(token.text[1:], base = 10)
+			if !ok {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+			if upper == 0 {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+
+			node.lower = -1
+			node.upper = cast(int)upper
+
+		case len(token.text) - 1: // {N,}
+			lower, ok := strconv.parse_u64_of_base(token.text[:comma], base = 10)
+			if !ok {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+
+			node.lower = cast(int)lower
+			node.upper = -1
+
+		case: // {N,M}
+			lower, lower_ok := strconv.parse_u64_of_base(token.text[:comma], base = 10)
+			if !lower_ok {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+			upper, upper_ok := strconv.parse_u64_of_base(token.text[comma+1:], base = 10)
+			if !upper_ok {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+			if lower > upper {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+			if upper == 0 {
+				return nil, Invalid_Repetition{ pos = token.pos }
+			}
+
+			node.lower = cast(int)lower
+			node.upper = cast(int)upper
+		}
+
+		result = node
+
+	case .Optional:
+		node := new(Node_Optional)
+		node.inner = left
+		result = node
+	case .Optional_Non_Greedy:
+		node := new(Node_Optional_Non_Greedy)
+		node.inner = left
+		result = node
+
+	case .EOF:
+		return nil, Unexpected_EOF{ pos = token.pos }
+
+	case:
+		return nil, Invalid_Token{ pos = token.pos, kind = token.kind }
+	}
+
+	return
+}
+
+parse_expression :: proc(p: ^Parser, rbp: int) -> (result: Node, err: Error) {
+	token := p.cur_token
+
+	advance(p) or_return
+	left := null_denotation(p, token) or_return
+
+	token = p.cur_token
+	for rbp < left_binding_power(token.kind) {
+		advance(p) or_return
+		left = left_denotation(p, token, left) or_return
+		token = p.cur_token
+	}
+
+	return left, nil
+}
+
+parse :: proc(str: string, flags: common.Flags) -> (result: Node, err: Error) {
+	if len(str) == 0 {
+		node := new(Node_Group)
+		return node, nil
+	}
+
+	p: Parser
+	p.flags = flags
+
+	tokenizer.init(&p.t, str, flags)
+
+	p.cur_token = tokenizer.scan(&p.t)
+	if p.cur_token.kind == .Invalid {
+		return nil, Invalid_Unicode { pos = 0 }
+	}
+
+	node := parse_expression(&p, 0) or_return
+	result = node
+
+	return
+}