Regular Expressions 101

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  • Unit Tests (17)
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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Character class intersection
    [\w&&[^\d]]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
Processing...

Test String

Code Generator

Generated Code

import re regex = re.compile(r"(?:(?<=(?:import|export)[^`'\"]*from\s+[`'\"])(?<path1>[^`'\"]+)(?=(?:'|\"|`)))|(?:\b(?:import|export)(?:\s+|\s*\(\s*)[`'\"](?<path2>[^`'\"]+)[`'\"])", flags=re.MULTILINE) test_str = ("import { defaultTemplateProcessor } from './lib/default-template-processor.js';\n" "import { SVGTemplateResult, TemplateResult } from './lib/template-result.js';\n" "export { DefaultTemplateProcessor, defaultTemplateProcessor } from './lib/default-template-processor.js';\n" "export { directive, isDirective } from './lib/directive.js';\n" "export { removeNodes, reparentNodes } from './lib/dom.js';\n" "export { noChange, nothing } from './lib/part.js';\n" "export { AttributeCommitter, AttributePart, BooleanAttributePart, EventPart, isIterable, isPrimitive, NodePart, PropertyCommitter, PropertyPart } from './lib/parts.js';\n" "export { parts, render } from './lib/render.js';\n" "export { templateCaches, templateFactory } from './lib/template-factory.js';\n" "export { TemplateInstance } from './lib/template-instance.js';\n" "export { SVGTemplateResult, TemplateResult } from './lib/template-result.js';\n" "export { createMarker, isTemplatePartActive, Template } from './lib/template.js';\n" "import { render } from 'lit-html/lib/shady-render.js';\n" "import { UpdatingElement } from './lib/updating-element.js';\n" "export * from './lib/updating-element.js';\n" "export * from './lib/decorators.js';\n" "export { html, svg, TemplateResult, SVGTemplateResult } from 'lit-html/lit-html.js';\n" "import { supportsAdoptingStyleSheets } from './lib/css-tag.js';\n" "export * from './lib/css-tag.js';\n" "import { LitElement } from 'lit-element';\n" "import { IronMeta } from '@polymer/iron-meta/iron-meta.js';\n" "import { whenOnline } from 'hadron-core/lib/utils/async.js';\n" "import { apiUrl, apiVersion } from '../../src/config.js';\n" "import { importModule, dynamicImportAvailable } from '../../src/dynamic-imports-polyfill.js';\n" "import observeProperties from 'hadron-core/lib/utils/object-property-observer.js';\n" "export { version };\n" "import { ElementMixin, version } from './lib/mixins/element-mixin.js';\n" "export { html } from './lib/utils/html-tag.js';\n\n" "class Foo {\n\n" " constructor() {\n" " import(`foo.js`);\n" " import(`${foo}`);\n" " import('bar.js');\n" " } \n\n" "}") matches = regex.finditer(test_str) for match_num, match in enumerate(matches, start=1): print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}") for group_num, group in enumerate(match.groups(), start=1): print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html