Refactor MTex

manimlib/mobject/svg/mtex_mobject.py

@@ -6,7 +6,7 @@ import itertools as it
 from types import MethodType
 from typing import Iterable, Union, Sequence
 
-from manimlib.constants import WHITE
+from manimlib.constants import BLACK, WHITE
 from manimlib.mobject.svg.svg_mobject import SVGMobject
 from manimlib.mobject.types.vectorized_mobject import VGroup
 from manimlib.utils.color import color_to_int_rgb
@@ -32,6 +32,9 @@ SCALE_FACTOR_PER_FONT_POINT = 0.001
 class _TexSVG(SVGMobject):
     CONFIG = {
         "height": None,
+        "svg_default": {
+            "fill_color": BLACK,
+        },
         "stroke_width": 0,
         "stroke_color": WHITE,
         "path_string_config": {
@@ -80,25 +83,11 @@ class MTex(_TexSVG):
             self.use_plain_tex
         )
 
-    def get_file_path(self) -> str:
-        self.init_parser()
-        self.use_plain_file = any([
-            self.use_plain_tex,
-            self.color_cmd_repl_items,
-            self.base_color != WHITE
-        ])
-        return self.get_file_path_(use_plain_file=self.use_plain_file)
-
-    def get_file_path_(self, use_plain_file: bool) -> str:
+    def get_file_path(self, use_plain_file: bool = False) -> str:
         if use_plain_file:
-            content = "".join([
-                "{{",
-                self.get_color_command(self.color_to_int(self.base_color)),
-                self.string,
-                "}}"
-            ])
+            content = self.plain_string
         else:
-            content = self.get_labelled_string()
+            content = self.labelled_string
 
         full_tex = self.get_tex_file_body(content)
         with display_during_execution(f"Writing \"{self.string}\""):
@@ -128,27 +117,26 @@ class MTex(_TexSVG):
     def generate_mobject(self) -> None:
         super().generate_mobject()
 
-        glyphs = self.submobjects
-        if not glyphs:
+        if not self.submobjects:
             return
 
-        if self.use_plain_file:
-            file_path = self.get_file_path_(use_plain_file=False)
-            labelled_svg_glyphs = _TexSVG(file_path)
-            predefined_colors = [
-                labelled_glyph.get_fill_color()
-                for labelled_glyph in self.submobjects
-            ]
-        else:
-            labelled_svg_glyphs = self
-            predefined_colors = [self.base_color] * len(glyphs)
-
         glyph_labels = [
-            self.color_to_label(labelled_glyph.get_fill_color())
-            for labelled_glyph in labelled_svg_glyphs
+            self.color_to_label(glyph.get_fill_color())
+            for glyph in self.submobjects
         ]
-        for glyph, glyph_color in zip(glyphs, predefined_colors):
-            glyph.set_fill(glyph_color)
+
+        if any([
+            self.use_plain_tex,
+            self.color_cmd_repl_items,
+            self.base_color in (BLACK, WHITE)
+        ]):
+            file_path = self.get_file_path(use_plain_file=True)
+            glyphs = _TexSVG(file_path).submobjects
+            for glyph, plain_glyph in zip(self.submobjects, glyphs):
+                glyph.set_fill(plain_glyph.get_fill_color())
+        else:
+            glyphs = self.submobjects
+            self.set_fill(self.base_color)
 
         # Simply pack together adjacent mobjects with the same label.
         submob_labels, glyphs_lists = self.group_neighbours(
@@ -171,20 +159,18 @@ class MTex(_TexSVG):
     ## Static methods
 
     @staticmethod
-    def color_to_int(color: ManimColor) -> int:
+    def color_to_label(color: ManimColor) -> int:
         r, g, b = color_to_int_rgb(color)
         rg = r * 256 + g
-        return rg * 256 + b
-
-    @staticmethod
-    def color_to_label(color: ManimColor) -> int:
-        result = MTex.color_to_int(color)
-        if result == 16777215:  # white
+        rgb = rg * 256 + b
+        if rgb == 16777215:  # white
             return -1
-        return result
+        return rgb
 
     @staticmethod
     def get_color_command(label: int) -> str:
+        if label == -1:
+            label = 16777215  # white
         rg, b = divmod(label, 256)
         r, g = divmod(rg, 256)
         return "".join([
@@ -223,40 +209,83 @@ class MTex(_TexSVG):
         groups.append(new_group)
         return group_labels, groups
 
+    @staticmethod
+    def find_region_index(val: int, seq: list[int]) -> int:
+        # Returns an integer in `range(len(seq) + 1)` satisfying
+        # `seq[result - 1] <= val < seq[result]`
+        if not seq:
+            return 0
+        if val >= seq[-1]:
+            return len(seq)
+        result = 0
+        while val >= seq[result]:
+            result += 1
+        return result
+
+    @staticmethod
+    def lstrip(index: int, skipped_spans: list[tuple[int, int]]) -> int:
+        index_seq = list(it.chain(*skipped_spans))
+        region_index = MTex.find_region_index(index, index_seq)
+        if region_index % 2 == 1:
+            return index_seq[region_index]
+        return index
+
+    @staticmethod
+    def rstrip(index: int, skipped_spans: list[tuple[int, int]]) -> int:
+        index_seq = list(it.chain(*skipped_spans))
+        region_index = MTex.find_region_index(index - 1, index_seq)
+        if region_index % 2 == 1:
+            return index_seq[region_index - 1]
+        return index
+
+    @staticmethod
+    def strip(
+        tex_span: tuple[int, int], skipped_spans: list[tuple[int, int]]
+    ) -> tuple[int, int] | None:
+        result = (
+            MTex.lstrip(tex_span[0], skipped_spans),
+            MTex.rstrip(tex_span[1], skipped_spans)
+        )
+        if result[0] >= result[1]:
+            return None
+        return result
+
+    @staticmethod
+    def lslide(index: int, slid_spans: list[tuple[int, int]]) -> int:
+        slide_dict = dict(slid_spans)
+        while index in slide_dict.keys():
+            index = slide_dict[index]
+        return index
+
+    @staticmethod
+    def rslide(index: int, slid_spans: list[tuple[int, int]]) -> int:
+        slide_dict = dict([
+            slide_span[::-1] for slide_span in slid_spans
+        ])
+        while index in slide_dict.keys():
+            index = slide_dict[index]
+        return index
+
+    @staticmethod
+    def slide(
+        tex_span: tuple[int, int], slid_spans: list[tuple[int, int]]
+    ) -> tuple[int, int] | None:
+        result = (
+            MTex.lslide(tex_span[0], slid_spans),
+            MTex.rslide(tex_span[1], slid_spans)
+        )
+        if result[0] >= result[1]:
+            return None
+        return result
+
     ## Parser
 
-    def init_parser(self) -> None:
-        self.additional_substrings = self.get_additional_substrings()
-        self.full_span = self.get_full_span()
-        self.backslash_indices = self.get_backslash_indices()
-        self.left_brace_indices, self.right_brace_indices = \
-            self.get_left_and_right_indices()
-        self.script_char_spans = self.get_script_char_spans()
-        self.skipped_indices = self.get_skipped_indices()
-        self.script_spans = self.get_script_spans()
-        self.script_content_spans = self.get_script_content_spans()
-        self.double_braces_spans = self.get_double_braces_spans()
-        self.stripped_substrings = self.get_stripped_substrings()
-        self.specified_substrings = self.get_specified_substrings()
-        self.specified_spans, self.extended_specified_spans = \
-            self.get_specified_spans()
-        self.tex_span_list = self.get_tex_span_list()
-        self.extended_tex_span_list = self.get_extended_tex_span_list()
-        self.isolated_substrings = self.get_isolated_substrings()
-        self.containing_labels_dict = self.get_containing_labels_dict()
-        self.color_cmd_repl_items = self.get_color_cmd_repl_items()
-        self.span_repl_dict = self.get_span_repl_dict()
-
-    def get_additional_substrings(self) -> list[str]:
-        return list(it.chain(
-            self.tex_to_color_map.keys(),
-            self.isolate
-        ))
-
-    def get_full_span(self) -> tuple[int, int]:
+    @property
+    def full_span(self) -> tuple[int, int]:
         return (0, len(self.string))
 
-    def get_backslash_indices(self) -> list[int]:
+    @property
+    def backslash_indices(self) -> list[int]:
         # Newlines (`\\`) don't count.
         return [
             match_obj.end() - 1
@@ -264,7 +293,9 @@ class MTex(_TexSVG):
             if len(match_obj.group()) % 2 == 1
         ]
 
-    def get_left_and_right_indices(self) -> list[tuple[int, int]]:
+    def get_left_and_right_brace_indices(
+        self
+    ) -> tuple[list[tuple[int, int]], list[tuple[int, int]]]:
         string = self.string
         indices = list(filter(
             lambda index: index - 1 not in self.backslash_indices,
@@ -287,60 +318,69 @@ class MTex(_TexSVG):
                 right_brace_indices.append(index)
         if left_brace_indices_stack:
             raise ValueError("Missing '}' inserted")
+        # `right_brace_indices` is already sorted.
         return left_brace_indices, right_brace_indices
 
-    def get_script_char_spans(self) -> list[tuple[int, int]]:
+    @property
+    def left_brace_indices(self) -> list[tuple[int, int]]:
+        return self.get_left_and_right_brace_indices()[0]
+
+    @property
+    def right_brace_indices(self) -> list[tuple[int, int]]:
+        return self.get_left_and_right_brace_indices()[1]
+
+    @property
+    def skipped_spans(self) -> list[tuple[int, int]]:
         return [
             match_obj.span()
-            for match_obj in re.finditer(r"(\s*)[_^]\s*", self.string)
-            if match_obj.group(1)
-            or match_obj.start() - 1 not in self.backslash_indices
+            for match_obj in re.finditer(r"\s*([_^])\s*|(\s+)", self.string)
+            if match_obj.group(2) is not None
+            or match_obj.start(1) - 1 not in self.backslash_indices
         ]
 
-    def get_skipped_indices(self) -> list[int]:
-        return sorted(remove_list_redundancies([
-            match_obj.start()
-            for match_obj in re.finditer(r"\s", self.string)
-        ] + list(it.chain(*[
-            range(*script_char_span)
-            for script_char_span in self.script_char_spans
-        ]))))
+    def lstrip_span(self, index: int) -> int:
+        return self.lstrip(index, self.skipped_spans)
 
-    def get_script_spans(self) -> list[tuple[int, int]]:
-        string = self.string
+    def rstrip_span(self, index: int) -> int:
+        return self.rstrip(index, self.skipped_spans)
+
+    def strip_span(self, index: int) -> int:
+        return self.strip(index, self.skipped_spans)
+
+    @property
+    def script_char_spans(self) -> list[tuple[int, int]]:
+        return list(filter(
+            lambda tex_span: self.string[slice(*tex_span)].strip(),
+            self.skipped_spans
+        ))
+
+    @property
+    def script_content_spans(self) -> list[tuple[int, int]]:
         result = []
         brace_indices_dict = dict(zip(
             self.left_brace_indices, self.right_brace_indices
         ))
-        for char_begin, span_begin in self.script_char_spans:
+        for _, span_begin in self.script_char_spans:
             if span_begin in brace_indices_dict.keys():
                 span_end = brace_indices_dict[span_begin] + 1
             else:
                 pattern = re.compile(r"[a-zA-Z0-9]|\\[a-zA-Z]+")
-                match_obj = pattern.match(string, pos=span_begin)
+                match_obj = pattern.match(self.string, pos=span_begin)
                 if not match_obj:
                     script_name = {
                         "_": "subscript",
                         "^": "superscript"
                     }[script_char]
-                    log.warning(
+                    raise ValueError(
                         f"Unclear {script_name} detected while parsing. "
                         "Please use braces to clarify"
                     )
-                    continue
                 span_end = match_obj.end()
-            result.append((char_begin, span_end))
+            result.append((span_begin, span_end))
         return result
 
-    def get_script_content_spans(self) -> list[tuple[int, int]]:
-        return [
-            (script_char_span[1], script_span[1])
-            for script_char_span, script_span in zip(
-                self.script_char_spans, self.script_spans
-            )
-        ]
-
-    def get_double_braces_spans(self) -> list[tuple[int, int]]:
+    @property
+    def double_braces_spans(self) -> list[tuple[int, int]]:
         # Match paired double braces (`{{...}}`).
         result = []
         reversed_brace_indices_dict = dict(zip(
@@ -348,7 +388,7 @@ class MTex(_TexSVG):
         ))
         skip = False
         for prev_right_index, right_index in self.get_neighbouring_pairs(
-            sorted(reversed_brace_indices_dict.keys())
+            self.right_brace_indices
         ):
             if skip:
                 skip = False
@@ -363,74 +403,64 @@ class MTex(_TexSVG):
             skip = True
         return result
 
-    def get_stripped_substrings(self) -> list[str]:
-        result = remove_list_redundancies([
-            substr.strip()
-            for substr in self.additional_substrings
-        ])
+    @property
+    def additional_substrings(self) -> list[str]:
+        result = remove_list_redundancies(list(it.chain(
+            self.tex_to_color_map.keys(),
+            self.isolate
+        )))
         if "" in result:
             result.remove("")
         return result
 
-    def get_specified_substrings(self) -> list[str]:
-        return remove_list_redundancies([
-            self.string[slice(*double_braces_span)]
-            for double_braces_span in self.double_braces_spans
-        ] + list(filter(
-            lambda s: s in self.string,
-            self.stripped_substrings
-        )))
-
-    def get_specified_spans(
+    def get_tex_span_lists(
         self
     ) -> tuple[list[tuple[int, int]], list[tuple[int, int]]]:
-        tex_spans = sorted(remove_list_redundancies([
-            self.full_span,
-            *self.double_braces_spans,
-            *[
-                match_obj.span()
-                for substr in self.stripped_substrings
-                for match_obj in re.finditer(re.escape(substr), self.string)
-            ]
-        ]), key=lambda t: (t[0], -t[1]))
         result = []
         extended_result = []
-        script_spans_dict = dict(self.script_spans)
-        reversed_script_spans_dict = dict([
-            script_span[::-1] for script_span in self.script_spans
+        script_content_spans = self.script_content_spans
+        script_spans = [
+            (script_char_span[0], script_content_span[1])
+            for script_char_span, script_content_span in zip(
+                self.script_char_spans, script_content_spans
+            )
+        ]
+        tex_spans = remove_list_redundancies([
+            self.full_span,
+            *self.double_braces_spans,
+            *filter(lambda stripped_span: stripped_span is not None, [
+                self.strip_span(match_obj.span())
+                for substr in self.additional_substrings
+                for match_obj in re.finditer(re.escape(substr), self.string)
+            ]),
+            *script_content_spans
         ])
         for tex_span in tex_spans:
-            if tex_span in self.script_content_spans:
+            if tex_span in script_content_spans:
+                result.append(tex_span)
+                extended_result.append(tex_span)
                 continue
             span_begin, span_end = tex_span
-            extended_span_end = span_end
-            while span_end in reversed_script_spans_dict.keys():
-                span_end = reversed_script_spans_dict[span_end]
-            while extended_span_end in script_spans_dict.keys():
-                extended_span_end = script_spans_dict[extended_span_end]
-            specified_span = (span_begin, span_end)
-            extended_specified_span = (span_begin, extended_span_end)
-            if span_begin >= span_end:
+            shrinked_span = (span_begin, self.rslide(span_end, script_spans))
+            extended_span = (span_begin, self.lslide(span_end, script_spans))
+            if shrinked_span[0] >= shrinked_span[1]:
                 continue
-            if extended_specified_span in result:
+            if shrinked_span in result:
                 continue
-            result.append(specified_span)
-            extended_result.append(extended_specified_span)
+            result.append(shrinked_span)
+            extended_result.append(extended_span)
         return result, extended_result
 
-    def get_tex_span_list(self) -> list[tuple[int, int]]:
-        return self.specified_spans + self.script_content_spans
+    @property
+    def tex_span_list(self) -> list[tuple[int, int]]:
+        return self.get_tex_span_lists()[0]
 
-    def get_extended_tex_span_list(self) -> list[tuple[int, int]]:
-        return self.extended_specified_spans + self.script_content_spans
+    @property
+    def extended_tex_span_list(self) -> list[tuple[int, int]]:
+        return self.get_tex_span_lists()[1]
 
-    def get_isolated_substrings(self) -> list[str]:
-        return remove_list_redundancies([
-            self.string[slice(*tex_span)]
-            for tex_span in self.tex_span_list
-        ])
-
-    def get_containing_labels_dict(self) -> dict[tuple[int, int], list[int]]:
+    @property
+    def containing_labels_dict(self) -> dict[tuple[int, int], list[int]]:
         tex_span_list = self.tex_span_list
         result = {
             tex_span: []
@@ -449,40 +479,46 @@ class MTex(_TexSVG):
                         "Partially overlapping substrings detected: "
                         f"'{string_0}' and '{string_1}'"
                     )
-        result[self.full_span] = list(range(len(tex_span_list)))
+        result[self.full_span] = list(range(-1, len(tex_span_list)))
         return result
 
-    def get_color_cmd_repl_items(self) -> list[tuple[tuple[int, int], str]]:
-        color_related_command_items = [
-            ("color", 1, ""),
-            ("textcolor", 1, ""),
-            ("pagecolor", 1, "\\pagecolor{white}"),
-            ("colorbox", 1, "\\colorbox{white}"),
-            ("fcolorbox", 2, "\\fcolorbox{white}{white}"),
-        ]
+    @property
+    def color_cmd_repl_items(self) -> list[tuple[tuple[int, int], str]]:
+        color_related_command_dict = {
+            "color": (1, False),
+            "textcolor": (1, False),
+            "pagecolor": (1, True),
+            "colorbox": (1, True),
+            "fcolorbox": (2, True),
+        }
         result = []
-        string = self.string
         backslash_indices = self.backslash_indices
-        left_indices = self.left_brace_indices
-        brace_indices_dict = dict(zip(
-            self.left_brace_indices, self.right_brace_indices
-        ))
-        for cmd_name, n_braces, repl_str in color_related_command_items:
-            pattern = cmd_name + r"(?![a-zA-Z])"
-            for match_obj in re.finditer(pattern, string):
-                span_begin, span_end = match_obj.span()
-                span_begin -= 1
-                if span_begin not in backslash_indices:
-                    continue
-                for _ in range(n_braces):
-                    left_index = min(filter(
-                        lambda index: index >= span_end, left_indices
-                    ))
-                    span_end = brace_indices_dict[left_index] + 1
-                result.append(((span_begin, span_end), repl_str))
+        right_brace_indices = self.right_brace_indices
+        pattern = "".join([
+            r"\\",
+            "(",
+            "|".join(color_related_command_dict.keys()),
+            ")",
+            r"(?![a-zA-Z])"
+        ])
+        for match_obj in re.finditer(pattern, self.string):
+            span_begin, cmd_end = match_obj.span()
+            if span_begin not in backslash_indices:
+                continue
+            cmd_name = match_obj.group(1)
+            n_braces, substitute_cmd = color_related_command_dict[cmd_name]
+            span_end = right_brace_indices[self.find_region_index(
+                cmd_end, right_brace_indices
+            ) + n_braces - 1] + 1
+            if substitute_cmd:
+                repl_str = "\\" + cmd_name + n_braces * "{white}"
+            else:
+                repl_str = ""
+            result.append(((span_begin, span_end), repl_str))
         return result
 
-    def get_span_repl_dict(self) -> dict[tuple[int, int], str]:
+    @property
+    def span_repl_dict(self) -> dict[tuple[int, int], str]:
         indices, _, _, cmd_strings = zip(*sorted([
             (
                 tex_span[flag],
@@ -490,7 +526,7 @@ class MTex(_TexSVG):
                 -tex_span[1 - flag],
                 ("{{" + self.get_color_command(label), "}}")[flag]
             )
-            for label, tex_span in enumerate(self.tex_span_list)
+            for label, tex_span in enumerate(self.extended_tex_span_list)
             for flag in range(2)
         ]))
         result = {
@@ -502,7 +538,17 @@ class MTex(_TexSVG):
         result.update(self.color_cmd_repl_items)
         return result
 
-    def get_labelled_string(self) -> str:
+    @property
+    def plain_string(self) -> str:
+        return "".join([
+            "{{",
+            self.get_color_command(self.color_to_label(self.base_color)),
+            self.string,
+            "}}"
+        ])
+
+    @property
+    def labelled_string(self) -> str:
         if not self.span_repl_dict:
             return self.string
 
@@ -545,7 +591,6 @@ class MTex(_TexSVG):
                 ordered_containing_labels[1:], ordered_span_begins[1:]
             )
         ]
-        string_span_begins.insert(0, ordered_span_begins[0])
         string_span_ends = [
             next_begin if next_label in containing_labels else curr_end
             for next_begin, next_label, containing_labels, curr_end in zip(
@@ -553,49 +598,72 @@ class MTex(_TexSVG):
                 ordered_containing_labels[:-1], ordered_span_ends[:-1]
             )
         ]
-        string_span_ends.append(ordered_span_ends[-1])
+        string_spans = list(zip(
+            (ordered_span_begins[0], *string_span_begins),
+            (*string_span_ends, ordered_span_ends[-1])
+        ))
 
         string = self.string
-        left_indices = self.left_brace_indices
-        right_indices = self.right_brace_indices
-        skipped_indices = sorted(it.chain(
-            self.skipped_indices,
-            left_indices,
-            right_indices
-        ))
+        left_brace_indices = self.left_brace_indices
+        right_brace_indices = self.right_brace_indices
+        slid_spans = self.skipped_spans + [
+            (index, index + 1)
+            for index in left_brace_indices + right_brace_indices
+        ]
         result = []
-        for span_begin, span_end in zip(string_span_begins, string_span_ends):
-            while span_begin in skipped_indices:
-                span_begin += 1
-            if span_begin >= span_end:
-                result.append("")
+        for str_span in string_spans:
+            str_span = self.strip_span(str_span)
+            if str_span is None:
                 continue
-            while span_end - 1 in skipped_indices:
-                span_end -= 1
-            unclosed_left_brace = 0
-            unclosed_right_brace = 0
-            for index in range(span_begin, span_end):
-                if index in left_indices:
-                    unclosed_left_brace += 1
-                elif index in right_indices:
-                    if unclosed_left_brace == 0:
-                        unclosed_right_brace += 1
+            str_span = self.slide(str_span, slid_spans)
+            if str_span is None:
+                continue
+            unclosed_left_braces = 0
+            unclosed_right_braces = 0
+            for index in range(*str_span):
+                if index in left_brace_indices:
+                    unclosed_left_braces += 1
+                elif index in right_brace_indices:
+                    if unclosed_left_braces == 0:
+                        unclosed_right_braces += 1
                     else:
-                        unclosed_left_brace -= 1
+                        unclosed_left_braces -= 1
             result.append("".join([
-                unclosed_right_brace * "{",
-                string[span_begin:span_end],
-                unclosed_left_brace * "}"
+                unclosed_right_braces * "{",
+                string[slice(*str_span)],
+                unclosed_left_braces * "}"
             ]))
         return result
 
+    @property
+    def specified_substrings(self) -> list[str]:
+        return remove_list_redundancies([
+            self.string[slice(*double_braces_span)]
+            for double_braces_span in self.double_braces_spans
+        ] + list(filter(
+            lambda s: s in self.string,
+            self.additional_substrings
+        )))
+
+    def get_specified_substrings(self) -> list[str]:
+        return self.specified_substrings
+
+    @property
+    def isolated_substrings(self) -> list[str]:
+        return remove_list_redundancies([
+            self.string[slice(*tex_span)]
+            for tex_span in self.tex_span_list
+        ])
+
+    def get_isolated_substrings(self) -> list[str]:
+        return self.isolated_substrings
+
     ## Selector
 
     def find_span_components_of_custom_span(
         self,
         custom_span: tuple[int, int]
     ) -> list[tuple[int, int]] | None:
-        skipped_indices = self.skipped_indices
         tex_span_choices = sorted(filter(
             lambda tex_span: all([
                 tex_span[0] >= custom_span[0],
@@ -606,13 +674,13 @@ class MTex(_TexSVG):
         # Choose spans that reach the farthest.
         tex_span_choices_dict = dict(tex_span_choices)
 
-        span_begin, span_end = custom_span
         result = []
+        span_begin, span_end = custom_span
+        span_begin = self.rstrip_span(span_begin)
+        span_end = self.rstrip_span(span_end)
         while span_begin != span_end:
+            span_begin = self.lstrip_span(span_begin)
             if span_begin not in tex_span_choices_dict.keys():
-                if span_begin in skipped_indices:
-                    span_begin += 1
-                    continue
                 return None
             next_begin = tex_span_choices_dict[span_begin]
             result.append((span_begin, next_begin))
@@ -640,7 +708,7 @@ class MTex(_TexSVG):
         return VGroup(*[
             self.get_part_by_custom_span(match_obj.span())
             for match_obj in re.finditer(
-                re.escape(tex.strip()), self.string
+                re.escape(tex), self.string
             )
         ])