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Convert "Regex" to typst

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src/Warm-Ups/Regex/main.tex
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\documentclass[
solutions,
hidewarning,
]{../../../lib/tex/ormc_handout}
\usepackage{../../../lib/tex/macros}
\usepackage{xcolor}
\usepackage{soul}
\usepackage{hyperref}
\definecolor{Light}{gray}{.90}
\sethlcolor{Light}
\newcommand{\htexttt}[1]{\texttt{\hl{#1}}}
\title{The Regex Warm-Up}
\uptitler{\smallurl{}}
\subtitle{Prepared by Mark on \today}
\begin{document}
\maketitle
Last time, we discussed Deterministic Finite Automata. One interesting application of these mathematical objects is found in computer science: Regular Expressions. \par
This is often abbreviated \say{regex}, which is pronounced like \say{gif.}
\vspace{2mm}
Regex is a language used to specify patterns in a string. You can think of it as a concise way to define a DFA, using text instead of a huge graph. \par
Often enough, a clever regex pattern can do the work of a few hundred lines of code.
\vspace{2mm}
Like the DFAs we've studied, a regex pattern \textit{accepts} or \textit{rejects} a string. However, we don't usually use this terminology with regex, and instead say that a string \textit{matches} or \textit{doesn't match} a pattern.
\vspace{5mm}
Regex strings consist of characters, quantifiers, sets, and groups.
\vspace{5mm}
\textbf{Quantifiers} \par
Quantifiers specify how many of a character to match. \par
There are four of these: \htexttt{+}, \htexttt{*}, \htexttt{?}, and \htexttt{\{ \}}
\vspace{2mm}
\htexttt{+} means \say{match one or more of the preceding token} \par
\htexttt{*} means \say{match zero or more of the preceding token}
For example, the pattern \htexttt{ca+t} will match the following strings:
\begin{itemize}
\item \texttt{cat}
\item \texttt{caat}
\item \texttt{caaaaaaaat}
\end{itemize}
\htexttt{ca+t} will \textbf{not} match the string \texttt{ct}. \par
The pattern \htexttt{ca*t} will match all the strings above, including \texttt{ct}.
\vspace{2mm}
\htexttt{?} means \say{match one or none of the preceding token} \par
The pattern \htexttt{linea?r} will match only \texttt{linear} and \texttt{liner}.
\vspace{2mm}
Brackets \htexttt{\{min, max\}} are the most flexible quantifier. \par
They specify exactly how many tokens to match: \par
\htexttt{ab\{2\}a} will match only \texttt{abba}. \par
\htexttt{ab\{1,3\}a} will match only \texttt{aba}, \texttt{abba}, and \texttt{abbba}. \par
% spell:off
\htexttt{ab\{2,\}a} will match any \texttt{ab...ba} with at least two \texttt{b}s.
% spell:on
\vspace{5mm}
\problem{}
Write the patterns \htexttt{a*} and \htexttt{a+} using only \htexttt{\{ \}}.
\vfill
\problem{}
Draw a DFA equivalent to the regex pattern \htexttt{01*0}.
\vfill
\pagebreak
\textbf{Characters, Sets, and Groups} \par
In the previous section, we saw how we can specify characters literally: \par
\texttt{a+} means \say{one or more \texttt{a} character}
\vspace{2mm}
There are, of course, other ways we can specify characters.
\vspace{2mm}
The first such way is the \textit{set}, denoted \htexttt{[ ]}. A set can pretend to be any character inside it. \par
For example, \htexttt{m[aoy]th} will match \texttt{math}, \texttt{moth}, or \texttt{myth}. \par
\htexttt{a[01]+b} will match \texttt{a0b}, \texttt{a111b}, \texttt{a1100110b}, and any other similar string. \par
You may negate a set with a \htexttt{\textasciicircum}. \par
\htexttt{[\textasciicircum abc]} will match any character except \texttt{a}, \texttt{b}, or \texttt{c}, including symbols and spaces.
\vspace{2mm}
If we want to keep characters together, we can use the \textit{group}, denoted \htexttt{( )}. \par
Groups work exactly as you'd expect, representing an atomic\footnotemark{} group of characters. \par
\htexttt{a(01)+b} will match \texttt{a01b} and \texttt{a010101b}, but will \textbf{not} match \texttt{a0b}, \texttt{a1b}, or \texttt{a1100110b}.
\footnotetext{In other words, \say{unbreakable}}
\problem{}<regex>
You are now familiar with most of the tools regex has to offer. \par
Write patterns that match the following strings:
\begin{enumerate}[itemsep=1mm]
\item An ISO-8601 date, like \texttt{2022-10-29}. \par
\hint{Invalid dates like \texttt{2022-13-29} should also be matched.}
\item An email address. \par
\hint{Don't forget about subdomains, like \texttt{math.ucla.edu}.}
\item A UCLA room number, like \texttt{MS 5118} or \texttt{Kinsey 1220B}.
\item Any ISBN-10 of the form \texttt{0-316-00395-7}. \par
\hint{Remember that the check digit may be an \texttt{X}. Dashes are optional.}
\item A word of even length. \par
\hint{The set \texttt{[A-z]} contains every english letter, capitalized and lowercase. \\
\texttt{[a-z]} will only match lowercase letters.}
\item A word with exactly 3 vowels. \par
\hint{The special token \texttt{\textbackslash w} will match any word character. It is equivalent to \texttt{[A-z0-9\_]} \\ \texttt{\_} stands for a literal underscore.}
\item A word that has even length and exactly 3 vowels.
\item A sentence that does not start with a capital letter.
\end{enumerate}
\vfill
\problem{}
If you'd like to know more, check out \url{https://regexr.com}. It offers an interactive regex prompt, as well as a cheatsheet that explains every other regex token there is. \par
You will find a nice set of challenges at \url{https://alf.nu/RegexGolf}.
I especially encourage you to look into this if you are interested in computer science.
\end{document}

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#import "@local/handout:0.1.0": *
#show: handout.with(
title: [The Regex Warm-Up],
by: "Mark",
)
Last time, we discussed Deterministic Finite Automata. One interesting application of these mathematical objects is found in computer science: Regular Expressions. \
This is often abbreviated "regex," which is pronounced like "gif."
#v(2mm)
Regex is a language used to specify patterns in a string. You can think of it as a concise way to define a DFA, using text instead of a huge graph. \
Often enough, a clever regex pattern can do the work of a few hundred lines of code.
#v(2mm)
Like the DFAs we've studied, a regex pattern _accepts_ or _rejects_ a string. However, we don't usually use this terminology with regex, and instead say that a string _matches_ or _doesn't match_ a pattern.
#v(5mm)
Regex strings consist of characters, quantifiers, sets, and groups.
#v(5mm)
*Quantifiers* \
Quantifiers specify how many of a character to match. \
There are four of these: `+`, `*`, `?`, and `{ }`.
#v(4mm)
`+` means "match one or more of the preceding token" \
`*` means "match zero or more of the preceding token"
For example, the pattern `ca+t` will match the following strings:
- `cat`
- `caat`
- `caaaaaaaat`
`ca+t` will *not* match the string `ct`. \
The pattern `ca*t` will match all the strings above, including `ct`.
#v(4mm)
`?` means "match one or none of the preceding token" \
The pattern `linea?r` will match only `linear` and `liner`.
#v(4mm)
Brackets `{min, max}` are the most flexible quantifier. \
They specify exactly how many tokens to match: \
`ab{2}a` will match only `abba`. \
`ab{1,3}a` will match only `aba`, `abba`, and `abbba`. \
`ab{2,}a` will match any `ab...ba` with at least two `b`s. // spell:disable-line
#problem()
Write the patterns `a*` and `a+` using only `{ }`.
#v(1fr)
#problem()
Draw a DFA equivalent to the regex pattern `01*0`.
#v(1fr)
#pagebreak()
*Characters, Sets, and Groups* \
In the previous section, we saw how we can specify characters literally: \
`a+` means "one or more `a` characters" \
There are, of course, other ways we can specify characters.
#v(4mm)
The first such way is the _set_, denoted `[ ]`. A set can pretend to be any character inside it. \
For example, `m[aoy]th` will match `math`, `moth`, or `myth`. \
`a[01]+b` will match `a0b`, `a111b`, `a1100110b`, and any other similar string. \
#v(4mm)
We can negate a set with a `^`. \
`[^abc]` will match any single character except `a`, `b`, or `c`, including symbols and spaces.
#v(4mm)
If we want to keep characters together, we can use the _group_, denoted `( )`. \
Groups work exactly as you'd expect, representing an atomic#footnote([In other words, "unbreakable"]) group of characters. \
`a(01)+b` will match `a01b` and `a010101b`, but will *not* match `a0b`, `a1b`, or `a1100110b`.
#problem()
You are now familiar with most of the tools regex has to offer. \
Write patterns that match the following strings:
- An ISO-8601 date, like `2022-10-29`. \
#hint([Invalid dates like `2022-13-29` should also be matched.])
- An email address. \
#hint([Don't forget about subdomains, like `math.ucla.edu`.])
- A UCLA room number, like `MS 5118` or `Kinsey 1220B`.
- Any ISBN-10 of the form `0-316-00395-7`. \
#hint([Remember that the check digit may be an `X`. Dashes are optional.])
- A word of even length. \
#hint([
The set `[A-z]` contains every english letter, capitalized and lowercase. \
`[a-z]` will only match lowercase letters.
])
- A word with exactly 3 vowels. \
#hint([
The special token `\w` will match any word character. \
It is equivalent to `[A-z0-9_]`. `_` represents a literal underscore.
])
- A word that has even length and exactly 3 vowels.
- A sentence that does not start with a capital letter.
#v(1fr)
#problem()
If you'd like to know more, check out `https://regexr.com`.
It offers an interactive regex prompt,
as well as a cheatsheet that explains every other regex token there is. \
You can find a nice set of challenges at `https://alf.nu/RegexGolf`.