pyqt SyntaxHighlighter 正则表达式

PyQt中的`QSyntaxHighlighter`类可以用于对文本进行语法高亮显示。其实现原理是使用正则表达式匹配文本中的关键字，然后对匹配到的文本进行高亮处理。

以下是一个简单的示例，使用`QSyntaxHighlighter`类实现对Python代码中的关键字进行高亮显示：

import sys
from PyQt5.QtGui import QColor, QTextCharFormat, QFont, QSyntaxHighlighter
from PyQt5.QtWidgets import QApplication, QTextEdit


class PythonHighlighter(QSyntaxHighlighter):
    def __init__(self, parent=None):
        super(PythonHighlighter, self).__init__(parent)

        self.highlighting_rules = []

        keyword_format = QTextCharFormat()
        keyword_format.setForeground(QColor(255, 0, 0))
        keyword_format.setFontWeight(QFont.Bold)
        keywords = ["and", "as", "assert", "break", "class", "continue",
                    "def", "del", "elif", "else", "except", "False",
                    "finally", "for", "from", "global", "if", "import",
                    "in", "is", "lambda", "None", "nonlocal", "not",
                    "or", "pass", "raise", "return", "True", "try",
                    "while", "with", "yield"]
        for word in keywords:
            pattern = "\\b" + word + "\\b"
            rule = (pattern, keyword_format)
            self.highlighting_rules.append(rule)

        self.number_format = QTextCharFormat()
        self.number_format.setForeground(QColor(0, 128, 0))
        pattern = "\\b[0-9]+\\.?[0-9]*\\b"
        rule = (pattern, self.number_format)
        self.highlighting_rules.append(rule)

        self.string_format = QTextCharFormat()
        self.string_format.setForeground(QColor(128, 0, 128))
        pattern = "\".*\""
        rule = (pattern, self.string_format)
        self.highlighting_rules.append(rule)

    def highlightBlock(self, text):
        for pattern, format in self.highlighting_rules:
            expression = QRegularExpression(pattern)
            match_iterator = expression.globalMatch(text)
            while match_iterator.hasNext():
                match = match_iterator.next()
                self.setFormat(match.capturedStart(), match.capturedLength(), format)


if __name__ == '__main__':
    app = QApplication(sys.argv)
    editor = QTextEdit()
    highlighter = PythonHighlighter(editor.document())
    editor.show()
    sys.exit(app.exec_())

上述示例中，定义了一个名为`PythonHighlighter`的类，继承自`QSyntaxHighlighter`类。在`__init__`方法中，定义了三种高亮格式：关键字、数字和字符串。其中关键字的正则表达式使用了`\\b`来限制匹配单词边界，数字的正则表达式使用了`[0-9]+\\.?[0-9]*`，可以匹配整数和小数，字符串的正则表达式使用了`\".*\"`，可以匹配双引号括起来的任意字符串。

在`highlightBlock`方法中，根据预定义的正则表达式规则，对当前文本块中匹配到的文本进行相应的格式设置，从而实现语法高亮显示。最后在主函数中创建一个`QTextEdit`对象，并将其关联到自定义的`PythonHighlighter`对象上，运行程序即可看到效果。