A fairly major refactor / simplification.

src/ir/ast.rs

@@ -0,0 +1,172 @@
+use internment::ArcIntern;
+use pretty::{DocAllocator, Pretty};
+
+use crate::syntax::Location;
+
+type Variable = ArcIntern<String>;
+
+pub struct Program {
+    pub statements: Vec<Statement>,
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Program
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        let mut result = allocator.nil();
+
+        for stmt in self.statements.iter() {
+            result = result
+                .append(stmt.pretty(allocator))
+                .append(allocator.text(";"))
+                .append(allocator.hardline());
+        }
+
+        result
+    }
+}
+
+pub enum Statement {
+    Binding(Location, Variable, Expression),
+    Print(Location, Variable),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Statement
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Statement::Binding(_, var, expr) => allocator
+                .text(var.as_ref().to_string())
+                .append(allocator.space())
+                .append(allocator.text("="))
+                .append(allocator.space())
+                .append(expr.pretty(allocator)),
+            Statement::Print(_, var) => allocator
+                .text("print")
+                .append(allocator.space())
+                .append(allocator.text(var.as_ref().to_string())),
+        }
+    }
+}
+
+pub enum Expression {
+    Value(Location, Value),
+    Reference(Location, Variable),
+    Primitive(Location, Primitive, Vec<ValueOrRef>),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Expression
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Expression::Value(_, val) => val.pretty(allocator),
+            Expression::Reference(_, var) => allocator.text(var.as_ref().to_string()),
+            Expression::Primitive(_, op, exprs) if exprs.len() == 1 => {
+                op.pretty(allocator).append(exprs[0].pretty(allocator))
+            }
+            Expression::Primitive(_, op, exprs) if exprs.len() == 2 => {
+                let left = exprs[0].pretty(allocator);
+                let right = exprs[1].pretty(allocator);
+
+                left.append(allocator.space())
+                    .append(op.pretty(allocator))
+                    .append(allocator.space())
+                    .append(right)
+                    .parens()
+            }
+            Expression::Primitive(_, op, exprs) => {
+                allocator.text(format!("!!{:?} with {} arguments!!", op, exprs.len()))
+            }
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub enum Primitive {
+    Plus,
+    Minus,
+    Times,
+    Divide,
+}
+
+impl<'a> TryFrom<&'a str> for Primitive {
+    type Error = String;
+
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        match value {
+            "+" => Ok(Primitive::Plus),
+            "-" => Ok(Primitive::Minus),
+            "*" => Ok(Primitive::Times),
+            "/" => Ok(Primitive::Divide),
+            _ => Err(format!("Illegal primitive {}", value)),
+        }
+    }
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Primitive
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Primitive::Plus => allocator.text("+"),
+            Primitive::Minus => allocator.text("-"),
+            Primitive::Times => allocator.text("*"),
+            Primitive::Divide => allocator.text("/"),
+        }
+    }
+}
+
+pub enum ValueOrRef {
+    Value(Location, Value),
+    Ref(Location, ArcIntern<String>),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b ValueOrRef
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            ValueOrRef::Value(_, v) => v.pretty(allocator),
+            ValueOrRef::Ref(_, v) => allocator.text(v.as_ref().to_string()),
+        }
+    }
+}
+
+pub enum Value {
+    Number(Option<u8>, i64),
+}
+
+impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Value
+where
+    A: 'a,
+    D: ?Sized + DocAllocator<'a, A>,
+{
+    fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
+        match self {
+            Value::Number(opt_base, value) => {
+                let value_str = match opt_base {
+                    None => format!("{}", value),
+                    Some(2) => format!("0b{:b}", value),
+                    Some(8) => format!("0o{:o}", value),
+                    Some(10) => format!("0d{}", value),
+                    Some(16) => format!("0x{:x}", value),
+                    Some(_) => format!("!!{:x}!!", value),
+                };
+
+                allocator.text(value_str)
+            }
+        }
+    }
+}