feat(geth-engine): implement EventQL query execution

Author: YoEight

geth-eventql/src/codegen.rs

@@ -1,16 +1,79 @@
 use crate::{
-    Expr, ExprVisitor, Literal, NodeAttributes, Operation, Query, QueryVisitor, Var, parser::Record,
+    Expr, ExprVisitor, Literal, NodeAttributes, Operation, Query, QueryVisitor, Subject, Var,
+    parser::Record,
 };
 
+trait IntoLiteral {
+    fn into_literal(self) -> Literal;
+}
+
+impl IntoLiteral for String {
+    fn into_literal(self) -> Literal {
+        Literal::String(self)
+    }
+}
+
+impl IntoLiteral for &'_ str {
+    fn into_literal(self) -> Literal {
+        Literal::String(self.to_string())
+    }
+}
+
+impl IntoLiteral for &'_ String {
+    fn into_literal(self) -> Literal {
+        Literal::String(self.to_string())
+    }
+}
+
+impl IntoLiteral for u64 {
+    fn into_literal(self) -> Literal {
+        Literal::Integral(self as i64)
+    }
+}
+
+impl IntoLiteral for i64 {
+    fn into_literal(self) -> Literal {
+        Literal::Integral(self)
+    }
+}
+
+impl IntoLiteral for usize {
+    fn into_literal(self) -> Literal {
+        Literal::Integral(self as i64)
+    }
+}
+
 pub enum Instr {
+    EnterScope,
+    ExitScope,
     Push(Literal),
-    LoadVar(Var),
+    EnterSource,
+    ExitSource,
+    LoadVar,
+    LoadSource,
     Operation(Operation),
-    Array(usize),
+    Array,
     Rec(usize),
     Call(String),
 }
 
+impl Instr {
+    pub fn push(value: impl IntoLiteral) -> Self {
+        Instr::Push(value.into_literal())
+    }
+}
+
+pub enum SourceKind {
+    Events,
+    Subject,
+    Subquery,
+}
+
+pub struct LoadSource {
+    binding: String,
+    scope: u64,
+}
+
 pub fn codegen(query: &Query) -> Vec<Instr> {
     let mut state = Codegen::default();
 
@@ -27,6 +90,54 @@ pub struct Codegen {
 impl QueryVisitor for Codegen {
     type Inner<'a> = ExprCodegen<'a>;
 
+    fn enter_query(&mut self, attrs: &NodeAttributes) {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::EnterScope);
+    }
+
+    fn enter_from(&mut self, attrs: &NodeAttributes, _ident: &str) {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::EnterSource);
+    }
+
+    fn on_source_events(&mut self, attrs: &NodeAttributes, ident: &str) {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::push(ident));
+        self.instrs.push(Instr::push(0i64));
+        self.instrs.push(Instr::LoadSource);
+    }
+
+    fn on_source_subject(&mut self, attrs: &NodeAttributes, ident: &str, subject: &Subject) {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::push(ident));
+        for seg in subject.inner.iter() {
+            self.instrs.push(Instr::push(seg));
+        }
+
+        self.instrs.push(Instr::push(subject.inner.len()));
+        self.instrs.push(Instr::Array);
+        self.instrs.push(Instr::push(1i64));
+        self.instrs.push(Instr::LoadSource);
+    }
+
+    fn on_source_subquery(&mut self, attrs: &NodeAttributes, ident: &str) -> bool {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::push(ident));
+        self.instrs.push(Instr::push(2i64));
+        self.instrs.push(Instr::LoadSource);
+
+        true
+    }
+
+    fn exit_from(&mut self, attrs: &NodeAttributes, ident: &str) {
+        self.instrs.push(Instr::push(attrs.scope));
+        self.instrs.push(Instr::ExitSource);
+    }
+
+    fn exit_query(&mut self) {
+        self.instrs.push(Instr::ExitScope);
+    }
+
     fn expr_visitor<'a>(&'a mut self) -> Self::Inner<'a> {
         ExprCodegen { inner: self }
     }
@@ -41,8 +152,17 @@ impl ExprVisitor for ExprCodegen<'_> {
         self.inner.instrs.push(Instr::Push(lit.clone()));
     }
 
-    fn on_var(&mut self, _attrs: &NodeAttributes, var: &Var) {
-        self.inner.instrs.push(Instr::LoadVar(var.clone()));
+    fn on_var(&mut self, attrs: &NodeAttributes, var: &Var) {
+        self.inner.instrs.push(Instr::push(attrs.scope));
+
+        self.inner.instrs.push(Instr::push(var.name.as_str()));
+        for seg in &var.path {
+            self.inner.instrs.push(Instr::push(seg));
+        }
+
+        self.inner.instrs.push(Instr::push(var.path.len() + 1));
+        self.inner.instrs.push(Instr::Array);
+        self.inner.instrs.push(Instr::LoadVar);
     }
 
     fn enter_record_entry(&mut self, _attrs: &NodeAttributes, key: &str, _expr: &Expr) {
@@ -56,7 +176,8 @@ impl ExprVisitor for ExprCodegen<'_> {
     }
 
     fn exit_array(&mut self, _attrs: &NodeAttributes, values: &[Expr]) {
-        self.inner.instrs.push(Instr::Array(values.len()));
+        self.inner.instrs.push(Instr::push(values.len()));
+        self.inner.instrs.push(Instr::Array);
     }
 
     fn exit_app(&mut self, _attrs: &NodeAttributes, name: &str, _params: &[Expr]) {