Regular Expressions 101

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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]
  • 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"\G(?|(?:(?:\s+)(*MARK:T_WHITESPACE))|(?:(?:\/\/[^\n]*\n)(*MARK:T_COMMENT))|(?:(?:(?<=\b)true\b)(*MARK:T_BOOL_TRUE))|(?:(?:(?<=\b)false\b)(*MARK:T_BOOL_FALSE))|(?:(?:(?<=\b)null\b)(*MARK:T_NULL))|(?:(?:(?<=\b)Project\b)(*MARK:T_PROJECT))|(?:(?:(?<=\b)Table\b)(*MARK:T_TABLE))|(?:(?:(?<=\b)as\b)(*MARK:T_TABLE_ALIAS))|(?:(?:(?<=\b)(Indexes|indexes)\b)(*MARK:T_TABLE_INDEXES))|(?:(?:(Ref|ref))(*MARK:T_TABLE_REF))|(?:(?:(?<=\b)TableGroup\b)(*MARK:T_TABLE_GROUP))|(?:(?:(?<=\b)(Enum|enum)\b)(*MARK:T_ENUM))|(?:(?:(?<=\b)(primary\ske|pk)\b)(*MARK:T_TABLE_SETTING_PK))|(?:(?:(?<=\b)unique\b)(*MARK:T_TABLE_SETTING_UNIQUE))|(?:(?:(?<=\b)increment\b)(*MARK:T_TABLE_SETTING_INCREMENT))|(?:(?:(?<=\b)default\b)(*MARK:T_TABLE_SETTING_DEFAULT))|(?:(?:(?<=\b)null\b)(*MARK:T_TABLE_SETTING_NULL))|(?:(?:(?<=\b)not\snull\b)(*MARK:T_TABLE_SETTING_NOT_NULL))|(?:(?:(?<=\b)cascade\b)(*MARK:T_REF_ACTION_CASCADE))|(?:(?:(?<=\b)restrict\b)(*MARK:T_REF_ACTION_RESTRICT))|(?:(?:(?<=\b)set\snull\b)(*MARK:T_REF_ACTION_SET_NULL))|(?:(?:(?<=\b)set\default\b)(*MARK:T_REF_ACTION_SET_DEFAULT))|(?:(?:(?<=\b)no\saction\b)(*MARK:T_REF_ACTION_NO_ACTION))|(?:(?:(?<=\b)delete\b)(*MARK:T_REF_ACTION_DELETE))|(?:(?:(?<=\b)update\b)(*MARK:T_REF_ACTION_UPDATE))|(?:(?:note:)(*MARK:T_SETTING_NOTE))|(?:(?:(?<=\b)Note\b)(*MARK:T_NOTE))|(?:(?:[0-9]+\.[0-9]+)(*MARK:T_FLOAT))|(?:(?:[0-9]+)(*MARK:T_INT))|(?:(?:('{3}|[\"']{1})([^'\"][\s\S]*?)\1)(*MARK:T_QUOTED_STRING))|(?:(?:(`{1})([\s\S]+?)\1)(*MARK:T_EXPRESSION))|(?:(?:[a-zA-Z0-9_]+)(*MARK:T_WORD))|(?:(?:\\n)(*MARK:T_EOL))|(?:(?:\()(*MARK:T_LPAREN))|(?:(?:\))(*MARK:T_RPAREN))|(?:(?:{)(*MARK:T_LBRACE))|(?:(?:})(*MARK:T_RBRACE))|(?:(?:\[)(*MARK:T_LBRACK))|(?:(?:\])(*MARK:T_RBRACK))|(?:(?:\>)(*MARK:T_GT))|(?:(?:\<)(*MARK:T_LT))|(?:(?:,)(*MARK:T_COMMA))|(?:(?::)(*MARK:T_COLON))|(?:(?:\-)(*MARK:T_MINUS))|(?:(?:\.)(*MARK:T_DOT))|(?:(?:.+?)(*MARK:T_UNKNOWN)))", flags=re.DOTALL | re.UNICODE | re.MULTILINE) test_str = ("Project test {\n" " database_type: 'PostgreSQL'\n" " Note: 'Description of the project'\n" "}\n\n" "//// -- LEVEL 1\n" "//// -- Tables and References\n\n" "// Creating tables\n" "Table users as U {\n" " id int [pk, unique, increment] // auto-increment\n" " full_name varchar [not null, unique, default: 1]\n" " created_at timestamp\n" " country_code int\n" " type int\n" " note int\n" " Note: 'khong hieu duoc'\n" "}\n\n" "Table merchants {\n" " id int\n" "}\n\n" "Table countries {\n" " code int [pk]\n" " name varchar\n" " continent_name varchar\n" "}\n\n" "// Creating references\n" "// You can also define relationship separately\n" "// > many-to-one; < one-to-many; - one-to-one\n" "Ref{\n" " U.country_code > countries.code\n" " merchants.country_code > countries.code\n" "}\n\n" "//----------------------------------------------//\n\n" "//// -- LEVEL 2\n" "//// -- Adding column settings\n\n" "Table order_items {\n" " order_id int [ref: > orders.id]\n" " product_id int\n" " quantity int [default: 1] // default value\n" "}\n\n" "Ref: order_items.product_id > products.id\n\n" "Table orders {\n" " id int [pk] // primary key\n" " user_id int [not null, unique]\n" " status varchar\n" " created_at varchar [note: '''When order created'''] // add column note\n" "}\n\n" "Table int {\n" " id int\n" "}\n\n" "//----------------------------------------------//\n\n" "//// -- Level 3\n" "//// -- Enum, Indexes\n\n" "// Enum for 'products' table below\n" "Enum products_status {\n" " out_of_stock\n" " in_stock\n" " running_low [note: 'less than 20'] // add column note\n" "}\n\n" "// Indexes: You can define a single or multi-column index\n" "Table products {\n" " id int [pk]\n" " name varchar\n" " merchant_id int [not null]\n" " price int\n" " status products_status\n" " created_at datetime [default: `now()`]\n\n" " Indexes {\n" " (merchant_id, status) [name:'product_status', type: hash]\n" " id [unique]\n" " }\n" "}\n\n" "Ref: products.merchant_id > merchants.id // many-to-one\n\n" "TableGroup hello_world {\n" " just_test\n" " just_a_test\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