More utility functions

- join("a", "b", "c", sep: ", ")
- int("12")
- float("31.4e-1")
- str(10)
- sorted((3, 2, 1))

7 files changed, 161 insertions, 30 deletions

diff --git a/src/eval/array.rs b/src/eval/array.rs
index acf44ab2..bae89c4b 100644
--- a/src/eval/array.rs
+++ b/src/eval/array.rs
@@ -1,3 +1,4 @@
+use std::cmp::Ordering;
 use std::convert::TryFrom;
 use std::fmt::{self, Debug, Display, Formatter, Write};
 use std::iter::FromIterator;
@@ -80,6 +81,26 @@ impl Array {
         self.0.iter()
     }
 
+    /// Return a sorted version of this array.
+    ///
+    /// Returns an error if two values could not be compared.
+    pub fn sorted(mut self) -> StrResult<Self> {
+        let mut result = Ok(());
+        Rc::make_mut(&mut self.0).sort_by(|a, b| {
+            a.partial_cmp(b).unwrap_or_else(|| {
+                if result.is_ok() {
+                    result = Err(format!(
+                        "cannot compare {} with {}",
+                        a.type_name(),
+                        b.type_name(),
+                    ));
+                }
+                Ordering::Equal
+            })
+        });
+        result.map(|_| self)
+    }
+
     /// Repeat this array `n` times.
     pub fn repeat(&self, n: i64) -> StrResult<Self> {
         let count = usize::try_from(n)
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index b8561a87..f48312c8 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -5,13 +5,14 @@ mod array;
 #[macro_use]
 mod dict;
 #[macro_use]
+mod str;
+#[macro_use]
 mod value;
 mod capture;
 mod function;
 mod ops;
 mod scope;
 mod state;
-mod str;
 mod template;
 mod walk;
 
diff --git a/src/eval/ops.rs b/src/eval/ops.rs
index 6d34b877..c7a45614 100644
--- a/src/eval/ops.rs
+++ b/src/eval/ops.rs
@@ -291,12 +291,21 @@ pub fn compare(lhs: &Value, rhs: &Value) -> Option<Ordering> {
     match (lhs, rhs) {
         (Bool(a), Bool(b)) => a.partial_cmp(b),
         (Int(a), Int(b)) => a.partial_cmp(b),
-        (Int(a), Float(b)) => (*a as f64).partial_cmp(b),
-        (Float(a), Int(b)) => a.partial_cmp(&(*b as f64)),
         (Float(a), Float(b)) => a.partial_cmp(b),
         (Angle(a), Angle(b)) => a.partial_cmp(b),
         (Length(a), Length(b)) => a.partial_cmp(b),
+        (Relative(a), Relative(b)) => a.partial_cmp(b),
+        (Fractional(a), Fractional(b)) => a.partial_cmp(b),
         (Str(a), Str(b)) => a.partial_cmp(b),
+
+        // Some technically different things should be comparable.
+        (&Int(a), &Float(b)) => (a as f64).partial_cmp(&b),
+        (&Float(a), &Int(b)) => a.partial_cmp(&(b as f64)),
+        (&Length(a), &Linear(b)) if b.rel.is_zero() => a.partial_cmp(&b.abs),
+        (&Relative(a), &Linear(b)) if b.abs.is_zero() => a.partial_cmp(&b.rel),
+        (&Linear(a), &Length(b)) if a.rel.is_zero() => a.abs.partial_cmp(&b),
+        (&Linear(a), &Relative(b)) if a.abs.is_zero() => a.rel.partial_cmp(&b),
+
         _ => Option::None,
     }
 }
diff --git a/src/eval/str.rs b/src/eval/str.rs
index a358cd9f..099a4363 100644
--- a/src/eval/str.rs
+++ b/src/eval/str.rs
@@ -1,3 +1,4 @@
+use std::borrow::Borrow;
 use std::convert::TryFrom;
 use std::fmt::{self, Debug, Display, Formatter, Write};
 use std::ops::{Add, AddAssign, Deref};
@@ -5,6 +6,16 @@ use std::ops::{Add, AddAssign, Deref};
 use crate::diag::StrResult;
 use crate::util::EcoString;
 
+/// Create a new [`Str`] from a format string.
+macro_rules! format_str {
+    ($($tts:tt)*) => {{
+        use std::fmt::Write;
+        let mut s = $crate::util::EcoString::new();
+        write!(s, $($tts)*).unwrap();
+        $crate::eval::Str::from(s)
+    }};
+}
+
 /// A string value with inline storage and clone-on-write semantics.
 #[derive(Default, Clone, Eq, PartialEq, Ord, PartialOrd)]
 pub struct Str(EcoString);
@@ -92,6 +103,18 @@ impl AddAssign for Str {
     }
 }
 
+impl AsRef<str> for Str {
+    fn as_ref(&self) -> &str {
+        self
+    }
+}
+
+impl Borrow<str> for Str {
+    fn borrow(&self) -> &str {
+        self
+    }
+}
+
 impl From<char> for Str {
     fn from(c: char) -> Self {
         Self(c.into())
diff --git a/src/eval/value.rs b/src/eval/value.rs
index 5edf0362..77cb766c 100644
--- a/src/eval/value.rs
+++ b/src/eval/value.rs
@@ -88,6 +88,11 @@ impl Value {
     {
         T::cast(self)
     }
+
+    /// Join the value with another value.
+    pub fn join(self, rhs: Self) -> StrResult<Self> {
+        ops::join(self, rhs)
+    }
 }
 
 impl Default for Value {
diff --git a/src/library/mod.rs b/src/library/mod.rs
index ca99d43b..102291cc 100644
--- a/src/library/mod.rs
+++ b/src/library/mod.rs
@@ -17,8 +17,8 @@ use std::convert::TryFrom;
 use std::rc::Rc;
 
 use crate::color::{Color, RgbaColor};
-use crate::diag::TypResult;
-use crate::eval::{Arguments, EvalContext, Scope, State, Str, Template, Value};
+use crate::diag::{At, TypResult};
+use crate::eval::{Arguments, Array, EvalContext, Scope, State, Str, Template, Value};
 use crate::font::{FontFamily, FontStretch, FontStyle, FontWeight, VerticalFontMetric};
 use crate::geom::*;
 use crate::layout::LayoutNode;
@@ -59,13 +59,18 @@ pub fn new() -> Scope {
     // Utility.
     std.def_func("type", type_);
     std.def_func("repr", repr);
-    std.def_func("len", len);
-    std.def_func("rgb", rgb);
+    std.def_func("join", join);
+    std.def_func("int", int);
+    std.def_func("float", float);
+    std.def_func("str", str);
     std.def_func("abs", abs);
     std.def_func("min", min);
     std.def_func("max", max);
+    std.def_func("rgb", rgb);
     std.def_func("lower", lower);
     std.def_func("upper", upper);
+    std.def_func("len", len);
+    std.def_func("sorted", sorted);
 
     // Colors.
     std.def_const("white", RgbaColor::WHITE);
diff --git a/src/library/utility.rs b/src/library/utility.rs
index 0ece88ac..19dfc3ec 100644
--- a/src/library/utility.rs
+++ b/src/library/utility.rs
@@ -15,34 +15,65 @@ pub fn repr(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
     Ok(args.expect::<Value>("value")?.to_string().into())
 }
 
-/// `len`: The length of a string, an array or a dictionary.
-pub fn len(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
-    let Spanned { v, span } = args.expect("collection")?;
+/// `join`: Join a sequence of values, optionally interspersing it with another
+/// value.
+pub fn join(_: &mut EvalContext, args: &mut Arguments) -> 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>();
+
+    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)
+}
+
+/// `int`: Try to convert a value to a integer.
+pub fn int(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("value")?;
     Ok(Value::Int(match v {
-        Value::Str(v) => v.len(),
-        Value::Array(v) => v.len(),
-        Value::Dict(v) => v.len(),
-        _ => bail!(span, "expected string, array or dictionary"),
+        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()),
     }))
 }
 
-/// `rgb`: Create an RGB(A) color.
-pub fn rgb(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
-    Ok(Value::Color(Color::Rgba(
-        if let Some(string) = args.eat::<Spanned<Str>>() {
-            match RgbaColor::from_str(&string.v) {
-                Ok(color) => color,
-                Err(_) => bail!(string.span, "invalid color"),
-            }
-        } else {
-            let r = args.expect("red component")?;
-            let g = args.expect("green component")?;
-            let b = args.expect("blue component")?;
-            let a = args.eat().unwrap_or(1.0);
-            let f = |v: f64| (v.clamp(0.0, 1.0) * 255.0).round() as u8;
-            RgbaColor::new(f(r), f(g), f(b), f(a))
+/// `float`: Try to convert a value to a float.
+pub fn float(_: &mut EvalContext, args: &mut Arguments) -> 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()),
+    }))
+}
+
+/// `str`: Try to convert a value to a string.
+pub fn str(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("value")?;
+    Ok(Value::Str(match v {
+        Value::Int(v) => format_str!("{}", v),
+        Value::Float(v) => format_str!("{}", v),
+        Value::Str(v) => v,
+        v => bail!(span, "cannot convert {} to string", v.type_name()),
+    }))
 }
 
 /// `abs`: The absolute value of a numeric value.
@@ -91,6 +122,25 @@ fn minmax(args: &mut Arguments, goal: Ordering) -> TypResult<Value> {
     Ok(extremum)
 }
 
+/// `rgb`: Create an RGB(A) color.
+pub fn rgb(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    Ok(Value::Color(Color::Rgba(
+        if let Some(string) = args.eat::<Spanned<Str>>() {
+            match RgbaColor::from_str(&string.v) {
+                Ok(color) => color,
+                Err(_) => bail!(string.span, "invalid color"),
+            }
+        } else {
+            let r = args.expect("red component")?;
+            let g = args.expect("green component")?;
+            let b = args.expect("blue component")?;
+            let a = args.eat().unwrap_or(1.0);
+            let f = |v: f64| (v.clamp(0.0, 1.0) * 255.0).round() as u8;
+            RgbaColor::new(f(r), f(g), f(b), f(a))
+        },
+    )))
+}
+
 /// `lower`: Convert a string to lowercase.
 pub fn lower(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
     Ok(args.expect::<Str>("string")?.to_lowercase().into())
@@ -100,3 +150,20 @@ pub fn lower(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
 pub fn upper(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
     Ok(args.expect::<Str>("string")?.to_uppercase().into())
 }
+
+/// `len`: The length of a string, an array or a dictionary.
+pub fn len(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("collection")?;
+    Ok(Value::Int(match v {
+        Value::Str(v) => v.len(),
+        Value::Array(v) => v.len(),
+        Value::Dict(v) => v.len(),
+        _ => bail!(span, "expected string, array or dictionary"),
+    }))
+}
+
+/// `sorted`: The sorted version of an array.
+pub fn sorted(_: &mut EvalContext, args: &mut Arguments) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect::<Spanned<Array>>("array")?;
+    Ok(Value::Array(v.sorted().at(span)?))
+}