3 files changed, 412 insertions, 0 deletions
diff --git a/src/library/utility/math.rs b/src/library/utility/math.rs
new file mode 100644
index 00000000..795f39fd
--- /dev/null
+++ b/src/library/utility/math.rs
@@ -0,0 +1,114 @@
+use std::cmp::Ordering;
+
+use crate::library::prelude::*;
+
+/// The absolute value of a numeric value.
+pub fn abs(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("numeric value")?;
+    Ok(match v {
+        Value::Int(v) => Value::Int(v.abs()),
+        Value::Float(v) => Value::Float(v.abs()),
+        Value::Length(v) => Value::Length(v.abs()),
+        Value::Angle(v) => Value::Angle(v.abs()),
+        Value::Relative(v) => Value::Relative(v.abs()),
+        Value::Fractional(v) => Value::Fractional(v.abs()),
+        Value::Linear(_) => bail!(span, "cannot take absolute value of a linear"),
+        v => bail!(span, "expected numeric value, found {}", v.type_name()),
+    })
+}
+
+/// The minimum of a sequence of values.
+pub fn min(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    minmax(args, Ordering::Less)
+}
+
+/// The maximum of a sequence of values.
+pub fn max(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    minmax(args, Ordering::Greater)
+}
+
+/// Find the minimum or maximum of a sequence of values.
+fn minmax(args: &mut Args, goal: Ordering) -> TypResult<Value> {
+    let mut extremum = args.expect::<Value>("value")?;
+    for Spanned { v, span } in args.all::<Spanned<Value>>()? {
+        match v.partial_cmp(&extremum) {
+            Some(ordering) => {
+                if ordering == goal {
+                    extremum = v;
+                }
+            }
+            None => bail!(
+                span,
+                "cannot compare {} with {}",
+                extremum.type_name(),
+                v.type_name(),
+            ),
+        }
+    }
+    Ok(extremum)
+}
+
+/// Whether an integer is even.
+pub fn even(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    Ok(Value::Bool(args.expect::<i64>("integer")? % 2 == 0))
+}
+
+/// Whether an integer is odd.
+pub fn odd(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    Ok(Value::Bool(args.expect::<i64>("integer")? % 2 != 0))
+}
+
+/// The modulo of two numbers.
+pub fn modulo(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v: v1, span: span1 } = args.expect("integer or float")?;
+    let Spanned { v: v2, span: span2 } = args.expect("integer or float")?;
+
+    let (a, b) = match (v1, v2) {
+        (Value::Int(a), Value::Int(b)) => match a.checked_rem(b) {
+            Some(res) => return Ok(Value::Int(res)),
+            None => bail!(span2, "divisor must not be zero"),
+        },
+        (Value::Int(a), Value::Float(b)) => (a as f64, b),
+        (Value::Float(a), Value::Int(b)) => (a, b as f64),
+        (Value::Float(a), Value::Float(b)) => (a, b),
+        (Value::Int(_), b) | (Value::Float(_), b) => bail!(
+            span2,
+            format!("expected integer or float, found {}", b.type_name())
+        ),
+        (a, _) => bail!(
+            span1,
+            format!("expected integer or float, found {}", a.type_name())
+        ),
+    };
+
+    if b == 0.0 {
+        bail!(span2, "divisor must not be zero");
+    }
+
+    Ok(Value::Float(a % b))
+}
+
+/// Create a sequence of numbers.
+pub fn range(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let first = args.expect::<i64>("end")?;
+    let (start, end) = match args.eat::<i64>()? {
+        Some(second) => (first, second),
+        None => (0, first),
+    };
+
+    let step: i64 = match args.named("step")? {
+        Some(Spanned { v: 0, span }) => bail!(span, "step must not be zero"),
+        Some(Spanned { v, .. }) => v,
+        None => 1,
+    };
+
+    let mut x = start;
+    let mut seq = vec![];
+
+    while x.cmp(&end) == 0.cmp(&step) {
+        seq.push(Value::Int(x));
+        x += step;
+    }
+
+    Ok(Value::Array(Array::from_vec(seq)))
+}
diff --git a/src/library/utility/mod.rs b/src/library/utility/mod.rs
new file mode 100644
index 00000000..886cdc13
--- /dev/null
+++ b/src/library/utility/mod.rs
@@ -0,0 +1,187 @@
+//! Computational utility functions.
+
+mod math;
+mod numbering;
+
+pub use math::*;
+pub use numbering::*;
+
+use std::str::FromStr;
+
+use crate::library::prelude::*;
+use crate::library::text::{Case, TextNode};
+
+/// Ensure that a condition is fulfilled.
+pub fn assert(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect::<Spanned<bool>>("condition")?;
+    if !v {
+        bail!(span, "assertion failed");
+    }
+    Ok(Value::None)
+}
+
+/// The name of a value's type.
+pub fn type_(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    Ok(args.expect::<Value>("value")?.type_name().into())
+}
+
+/// The string representation of a value.
+pub fn repr(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    Ok(args.expect::<Value>("value")?.repr().into())
+}
+
+/// Join a sequence of values, optionally interspersing it with another value.
+pub fn join(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let span = args.span;
+    let sep = args.named::<Value>("sep")?.unwrap_or(Value::None);
+
+    let mut result = Value::None;
+    let mut iter = args.all::<Value>()?.into_iter();
+
+    if let Some(first) = iter.next() {
+        result = first;
+    }
+
+    for value in iter {
+        result = result.join(sep.clone()).at(span)?;
+        result = result.join(value).at(span)?;
+    }
+
+    Ok(result)
+}
+
+/// Convert a value to a integer.
+pub fn int(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("value")?;
+    Ok(Value::Int(match v {
+        Value::Bool(v) => v as i64,
+        Value::Int(v) => v,
+        Value::Float(v) => v as i64,
+        Value::Str(v) => match v.parse() {
+            Ok(v) => v,
+            Err(_) => bail!(span, "invalid integer"),
+        },
+        v => bail!(span, "cannot convert {} to integer", v.type_name()),
+    }))
+}
+
+/// Convert a value to a float.
+pub fn float(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("value")?;
+    Ok(Value::Float(match v {
+        Value::Int(v) => v as f64,
+        Value::Float(v) => v,
+        Value::Str(v) => match v.parse() {
+            Ok(v) => v,
+            Err(_) => bail!(span, "invalid float"),
+        },
+        v => bail!(span, "cannot convert {} to float", v.type_name()),
+    }))
+}
+
+/// Cconvert a value to a string.
+pub fn str(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("value")?;
+    Ok(Value::Str(match v {
+        Value::Int(v) => format_eco!("{}", v),
+        Value::Float(v) => format_eco!("{}", v),
+        Value::Str(v) => v,
+        v => bail!(span, "cannot convert {} to string", v.type_name()),
+    }))
+}
+
+/// Create an RGB(A) color.
+pub fn rgb(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    Ok(Value::from(
+        if let Some(string) = args.find::<Spanned<EcoString>>()? {
+            match RgbaColor::from_str(&string.v) {
+                Ok(color) => color,
+                Err(_) => bail!(string.span, "invalid hex string"),
+            }
+        } else {
+            struct Component(u8);
+
+            castable! {
+                Component,
+                Expected: "integer or relative",
+                Value::Int(v) => match v {
+                    0 ..= 255 => Self(v as u8),
+                    _ => Err("must be between 0 and 255")?,
+                },
+                Value::Relative(v) => if (0.0 ..= 1.0).contains(&v.get()) {
+                    Self((v.get() * 255.0).round() as u8)
+                } else {
+                    Err("must be between 0% and 100%")?
+                },
+            }
+
+            let Component(r) = args.expect("red component")?;
+            let Component(g) = args.expect("green component")?;
+            let Component(b) = args.expect("blue component")?;
+            let Component(a) = args.eat()?.unwrap_or(Component(255));
+            RgbaColor::new(r, g, b, a)
+        },
+    ))
+}
+
+/// Create a CMYK color.
+pub fn cmyk(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    struct Component(u8);
+
+    castable! {
+        Component,
+        Expected: "relative",
+        Value::Relative(v) => if (0.0 ..= 1.0).contains(&v.get()) {
+            Self((v.get() * 255.0).round() as u8)
+        } else {
+            Err("must be between 0% and 100%")?
+        },
+    }
+
+    let Component(c) = args.expect("cyan component")?;
+    let Component(m) = args.expect("magenta component")?;
+    let Component(y) = args.expect("yellow component")?;
+    let Component(k) = args.expect("key component")?;
+    Ok(Value::Color(CmykColor::new(c, m, y, k).into()))
+}
+
+/// The length of a string, an array or a dictionary.
+pub fn len(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("collection")?;
+    Ok(Value::Int(match v {
+        Value::Str(v) => v.len() as i64,
+        Value::Array(v) => v.len(),
+        Value::Dict(v) => v.len(),
+        v => bail!(
+            span,
+            "expected string, array or dictionary, found {}",
+            v.type_name(),
+        ),
+    }))
+}
+
+/// Convert a string to lowercase.
+pub fn lower(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    case(Case::Lower, args)
+}
+
+/// Convert a string to uppercase.
+pub fn upper(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    case(Case::Upper, args)
+}
+
+/// Change the case of a string or template.
+fn case(case: Case, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("string or template")?;
+    Ok(match v {
+        Value::Str(v) => Value::Str(case.apply(&v).into()),
+        Value::Template(v) => Value::Template(v.styled(TextNode::CASE, Some(case))),
+        v => bail!(span, "expected string or template, found {}", v.type_name()),
+    })
+}
+
+/// The sorted version of an array.
+pub fn sorted(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect::<Spanned<Array>>("array")?;
+    Ok(Value::Array(v.sorted().at(span)?))
+}
diff --git a/src/library/utility/numbering.rs b/src/library/utility/numbering.rs
new file mode 100644
index 00000000..0070873f
--- /dev/null
+++ b/src/library/utility/numbering.rs
@@ -0,0 +1,111 @@
+use crate::library::prelude::*;
+
+/// Converts an integer into one or multiple letters.
+pub fn letter(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    convert(Numbering::Letter, args)
+}
+
+/// Converts an integer into a roman numeral.
+pub fn roman(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    convert(Numbering::Roman, args)
+}
+
+/// Convert a number into a symbol.
+pub fn symbol(_: &mut Context, args: &mut Args) -> TypResult<Value> {
+    convert(Numbering::Symbol, args)
+}
+
+fn convert(numbering: Numbering, args: &mut Args) -> TypResult<Value> {
+    let n = args.expect::<usize>("non-negative integer")?;
+    Ok(Value::Str(numbering.apply(n)))
+}
+
+/// Allows to convert a number into letters, roman numerals and symbols.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
+pub enum Numbering {
+    Arabic,
+    Letter,
+    Roman,
+    Symbol,
+}
+
+impl Numbering {
+    /// Apply the numbering to the given number.
+    pub fn apply(self, mut n: usize) -> EcoString {
+        match self {
+            Self::Arabic => {
+                format_eco!("{}", n)
+            }
+            Self::Letter => {
+                if n == 0 {
+                    return '-'.into();
+                }
+
+                n -= 1;
+
+                let mut letters = vec![];
+                loop {
+                    letters.push(b'a' + (n % 26) as u8);
+                    n /= 26;
+                    if n == 0 {
+                        break;
+                    }
+                }
+
+                letters.reverse();
+                String::from_utf8(letters).unwrap().into()
+            }
+            Self::Roman => {
+                if n == 0 {
+                    return 'N'.into();
+                }
+
+                // Adapted from Yann Villessuzanne's roman.rs under the Unlicense, at
+                // https://github.com/linfir/roman.rs/
+                let mut fmt = EcoString::new();
+                for &(name, value) in ROMANS {
+                    while n >= value {
+                        n -= value;
+                        fmt.push_str(name);
+                    }
+                }
+
+                fmt
+            }
+            Self::Symbol => {
+                if n == 0 {
+                    return '-'.into();
+                }
+
+                let symbol = SYMBOLS[(n - 1) % SYMBOLS.len()];
+                let amount = ((n - 1) / SYMBOLS.len()) + 1;
+                std::iter::repeat(symbol).take(amount).collect()
+            }
+        }
+    }
+}
+
+static ROMANS: &'static [(&'static str, usize)] = &[
+    ("M̅", 1000000),
+    ("D̅", 500000),
+    ("C̅", 100000),
+    ("L̅", 50000),
+    ("X̅", 10000),
+    ("V̅", 5000),
+    ("I̅V̅", 4000),
+    ("M", 1000),
+    ("CM", 900),
+    ("D", 500),
+    ("CD", 400),
+    ("C", 100),
+    ("XC", 90),
+    ("L", 50),
+    ("XL", 40),
+    ("X", 10),
+    ("IX", 9),
+    ("V", 5),
+    ("IV", 4),
+    ("I", 1),
+];
+
+static SYMBOLS: &'static [char] = &['*', '†', '‡', '§', '‖', '¶'];