Start rewrite using query system.queries

1 files changed, 325 insertions, 0 deletions

diff --git a/src/chomp/ast-old/mod.rs b/src/chomp/ast-old/mod.rs
new file mode 100644
index 0000000..232381a
--- /dev/null
+++ b/src/chomp/ast-old/mod.rs
@@ -0,0 +1,325 @@
+use std::fmt::{self, Display};
+
+use proc_macro2::Span;
+
+use super::Name;
+
+pub mod error;
+pub mod substitute;
+
+#[derive(Clone, Copy, Debug, Default, Eq, PartialEq, Hash)]
+pub struct Epsilon;
+
+pub type Literal = String;
+
+#[derive(Clone, Debug)]
+pub struct Cat {
+    pub first: Box<NamedExpression>,
+    pub rest: Vec<(Option<Span>, NamedExpression)>,
+}
+
+impl Display for Cat {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "({}", self.first)?;
+        for (_, other) in &self.rest {
+            write!(f, " . {}", other)?;
+        }
+        write!(f, ")")
+    }
+}
+
+impl PartialEq for Cat {
+    fn eq(&self, other: &Self) -> bool {
+        self.first == other.first
+            && self.rest.len() == other.rest.len()
+            && self
+                .rest
+                .iter()
+                .zip(other.rest.iter())
+                .all(|((_, me), (_, them))| me == them)
+    }
+}
+
+impl Eq for Cat {}
+
+#[derive(Clone, Debug)]
+pub struct Alt {
+    pub first: Box<NamedExpression>,
+    pub rest: Vec<(Option<Span>, NamedExpression)>
+}
+
+impl Display for Alt {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "({}", self.first)?;
+        for (_, other) in &self.rest {
+            write!(f, " | {}", other)?;
+        }
+        write!(f, ")")
+    }
+}
+
+impl PartialEq for Alt {
+    fn eq(&self, other: &Self) -> bool {
+        self.first == other.first
+            && self.rest.len() == other.rest.len()
+            && self
+                .rest
+                .iter()
+                .zip(other.rest.iter())
+                .all(|((_, me), (_, them))| me == them)
+    }
+}
+
+impl Eq for Alt {}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Fix {
+    pub inner: Box<NamedExpression>,
+}
+
+impl Display for Fix {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "!{}", self.inner)
+    }
+}
+
+#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
+pub struct Variable {
+    pub index: usize,
+}
+
+impl Display for Variable {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "'{}", self.index)
+    }
+}
+
+/// A function invocation.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Call {
+    pub on: Box<NamedExpression>,
+    pub args: Vec<NamedExpression>,
+}
+
+impl Display for Call {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "({}", self.on)?;
+
+        for arg in self.args {
+            write!(f, " {}", arg)?;
+        }
+
+        write!(f, ")")
+    }
+}
+
+/// A function abstraction.
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Lambda {
+    pub args: Vec<Name>,
+    pub inner: Box<NamedExpression>,
+}
+
+impl Display for Lambda {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "/")?;
+        let mut iter = self.args.iter();
+        if let Some(arg) = iter.next() {
+            write!(f, "{}", arg)?;
+
+            for arg in iter {
+                write!(f, ", {}", arg)?;
+            }
+        }
+        write!(f, "/ {}", self.inner)
+    }
+}
+
+#[derive(Clone, Debug)]
+pub enum Expression {
+    /// Matches the empty string.
+    Epsilon(Epsilon),
+    /// Matches the literal string.
+    Literal(Literal),
+    /// Matches one term followed by another.
+    Cat(Cat),
+    /// Matches either one term or another.
+    Alt(Alt),
+    /// The least fix point of a term.
+    Fix(Fix),
+    /// A fixed point variable.
+    Variable(Variable),
+    /// A function invocation.
+    Call(Call),
+    /// A function abstraction.
+    Lambda(Lambda),
+}
+
+impl Expression {
+    pub fn try_into_lambda(self) -> Result<Lambda, Self> {
+        if let Self::Lambda(l) = self {
+            Ok(l)
+        } else {
+            Err(self)
+        }
+    }
+}
+
+impl Display for Expression {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Epsilon(_) => write!(f, "_"),
+            Self::Literal(l) => l.fmt(f),
+            Self::Cat(c) => c.fmt(f),
+            Self::Alt(a) => a.fmt(f),
+            Self::Fix(x) => x.fmt(f),
+            Self::Variable(v) => v.fmt(f),
+            Self::Lambda(p) => p.fmt(f),
+            Self::Call(c) => c.fmt(f),
+        }
+    }
+}
+
+impl PartialEq for Expression {
+    fn eq(&self, other: &Self) -> bool {
+        match self {
+            Self::Epsilon(_) => matches!(other, Self::Epsilon(_)),
+            Self::Literal(l) => {
+                if let Self::Literal(them) = other {
+                    l == them
+                } else {
+                    false
+                }
+            }
+            Self::Cat(c) => {
+                if let Self::Cat(them) = other {
+                    c == them
+                } else {
+                    false
+                }
+            }
+            Self::Alt(a) => {
+                if let Self::Alt(them) = other {
+                    a == them
+                } else {
+                    false
+                }
+            }
+            Self::Fix(f) => {
+                if let Self::Fix(them) = other {
+                    f == them
+                } else {
+                    false
+                }
+            }
+            Self::Variable(v) => {
+                if let Self::Variable(them) = other {
+                    v == them
+                } else {
+                    false
+                }
+            }
+            Self::Lambda(p) => {
+                if let Self::Lambda(them) = other {
+                    p == them
+                } else {
+                    false
+                }
+            }
+            Self::Call(c) => {
+                if let Self::Call(them) = other {
+                    c == them
+                } else {
+                    false
+                }
+            }
+        }
+    }
+}
+
+impl Eq for Expression {}
+
+impl From<Epsilon> for Expression {
+    fn from(eps: Epsilon) -> Self {
+        Self::Epsilon(eps)
+    }
+}
+
+impl From<Literal> for Expression {
+    fn from(lit: Literal) -> Self {
+        Self::Literal(lit)
+    }
+}
+
+impl From<Cat> for Expression {
+    fn from(cat: Cat) -> Self {
+        Self::Cat(cat)
+    }
+}
+
+impl From<Alt> for Expression {
+    fn from(alt: Alt) -> Self {
+        Self::Alt(alt)
+    }
+}
+
+impl From<Fix> for Expression {
+    fn from(fix: Fix) -> Self {
+        Self::Fix(fix)
+    }
+}
+
+impl From<Variable> for Expression {
+    fn from(var: Variable) -> Self {
+        Self::Variable(var)
+    }
+}
+
+impl From<Lambda> for Expression {
+    fn from(lambda: Lambda) -> Self {
+        Self::Lambda(lambda)
+    }
+}
+
+impl From<Call> for Expression {
+    fn from(call: Call) -> Self {
+        Self::Call(call)
+    }
+}
+
+#[derive(Clone, Debug)]
+pub struct NamedExpression {
+    pub name: Option<Name>,
+    pub expr: Expression,
+    pub span: Option<Span>,
+}
+
+impl Display for NamedExpression {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self.name {
+            Some(name) => write!(f, "({} : {})", self.expr, name),
+            None => self.expr.fmt(f),
+        }
+    }
+}
+
+impl PartialEq for NamedExpression {
+    fn eq(&self, other: &Self) -> bool {
+        self.expr == other.expr
+    }
+}
+
+impl Eq for NamedExpression {}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Let {
+    pub name: Name,
+    pub val: NamedExpression,
+    pub inner: Box<TopLevel>,
+}
+
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub enum TopLevel {
+    Let(Let),
+    Goal(NamedExpression),
+}