Proper Syntax Highlighting In Text Tkinter

Question

I got a a piece of code which can highlight the syntax for Python Using Tkinter Text Widget. However, I still can't highlight the function name after 'def' and Class name after 'class' and the package name after 'import'. If something obvious is missing, please be gentle and convey the message to me.

python.yaml

categories:
  keywords:
    color:  orange
    matches: ['False', 'None', 'True', 'and', 'as', 'assert', 'async', 'await', 'break', 'class', 'continue', 'def', 'del', 'elif', 'else', 'except', 'finally', 'for', 'from', 'global', 'if', 'import', 'in', 'is', 'lambda', 'nonlocal', 'not', 'or', 'pass', 'raise', 'return', 'try', 'while', 'with', 'yield']
  variables:
    color: red4
    matches: ['True', 'False', None]
  
  functions:
    color: "#525fe9"
    matches: ['abs',delattr','hash','memoryview','set','all','dict','help','min','setattr','any','dir','hex','next','slice','ascii','divmod','id','object','sorted','bin','enumerate','input','oct','staticmethod','bool','eval','int','open','str','breakpoint','exec','isinstance','ord','sum','bytearray','filter','issubclass','pow','super','bytes','float','iter','print','tuple','callable','format','len','property','type','chr','frozenset','list','range','vars','classmethod','getattr','locals','repr','zip','compile','globals','map','reversed','__import__','complex','hasattr','max',round']
numbers:
  color: pink
strings:
  color: "#e16d5b"

The highlighter.py helps to highlight words which it fetched from python.yaml file.

import tkinter as tk

import yaml


class Highlighter:
    def __init__(self, text_widget, syntax_file):
        self.text_widget = text_widget
        self.syntax_file = syntax_file
        self.categories = None
        self.numbers_color = "blue"

        self.disallowed_previous_chars = ["_", "-", "."]

        self.parse_syntax_file()

        self.text_widget.bind('<KeyRelease>', self.on_key_release)

    def on_key_release(self, event=None):
        self.highlight()

    def parse_syntax_file(self):
        with open(self.syntax_file, 'r') as stream:
            
            config = yaml.safe_load(stream)
            

        self.categories = config['categories']
        self.numbers_color = config['numbers']['color']
        self.strings_color = config['strings']['color']

        self.configure_tags()
    def callback_1(self,event):
        info_window = tk.Tk()
        info_window.overrideredirect(1)
        info_window.geometry("200x24+{0}+{1}".format(event.x_root-100, event.y_root-12))

        label = tk.Label(info_window, text="Word definition goes here.")
        label.pack(fill=tk.BOTH)

        info_window.bind_all("<Leave>", lambda e: info_window.destroy())  # Remove popup when pointer leaves the window
        info_window.mainloop()

    def configure_tags(self):
        for category in self.categories.keys():
            color = self.categories[category]['color']
            self.text_widget.tag_configure(category, foreground=color)

        self.text_widget.tag_configure("number", foreground=self.numbers_color)
        self.text_widget.tag_configure("string", foreground=self.strings_color)
        self.text_widget.tag_bind("string","<Enter>", self.callback_1)
    def highlight(self, event=None):
        length = tk.IntVar()
        for category in self.categories:
            matches = self.categories[category]['matches']
            for keyword in matches:
                start = 1.0
                keyword = keyword + "[^A-Za-z_-]"
                idx = self.text_widget.search(keyword, start, stopindex=tk.END, count=length, regexp=1)
                while idx:
                    char_match_found = int(str(idx).split('.')[1])
                    line_match_found = int(str(idx).split('.')[0])
                    if char_match_found > 0:
                        previous_char_index = str(line_match_found) + '.' + str(char_match_found - 1)
                        previous_char = self.text_widget.get(previous_char_index, previous_char_index + "+1c")

                        if previous_char.isalnum() or previous_char in self.disallowed_previous_chars:
                            end = f"{idx}+{length.get() - 1}c"
                            start = end
                            idx = self.text_widget.search(keyword, start, stopindex=tk.END, regexp=1)
                        else:
                            end = f"{idx}+{length.get() - 1}c"
                            self.text_widget.tag_add(category, idx, end)

                            start = end
                            idx = self.text_widget.search(keyword, start, stopindex=tk.END, regexp=1)
                    else:
                        end = f"{idx}+{length.get() - 1}c"
                        self.text_widget.tag_add(category, idx, end)

                        start = end
                        idx = self.text_widget.search(keyword, start, stopindex=tk.END, regexp=1)

        self.highlight_regex(r"(\d)+[.]?(\d)*", "number")
        self.highlight_regex(r"[\'][^\']*[\']", "string")
        self.highlight_regex(r"[\"][^\']*[\"]", "string")

    def highlight_regex(self, regex, tag):
        length = tk.IntVar()
        start = 1.0
        idx = self.text_widget.search(regex, start, stopindex=tk.END, regexp=1, count=length)
        while idx:
            end = f"{idx}+{length.get()}c"
            self.text_widget.tag_add(tag, idx, end)
            self.text_widget.tag_bind("string","<Enter>", self.callback_1)
            start = end
            idx = self.text_widget.search(regex, start, stopindex=tk.END, regexp=1, count=length)
        

if __name__ == '__main__':
    w = tk.Tk()
    x=tk.Text(w)
    x.pack(fill=tk.BOTH,expand=1)
    h = Highlighter(x, 'Path/to/python.yaml')
    w.mainloop()