Simplified file structure

src/core/Compare.go

@@ -0,0 +1,46 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/ast"
+	"git.akyoto.dev/cli/q/src/errors"
+	"git.akyoto.dev/cli/q/src/expression"
+	"git.akyoto.dev/cli/q/src/token"
+)
+
+// Compare evaluates a boolean expression.
+func (f *Function) Compare(comparison *expression.Expression) error {
+	left := comparison.Children[0]
+	right := comparison.Children[1]
+
+	if left.IsLeaf() && left.Token.Kind == token.Identifier {
+		name := left.Token.Text(f.File.Bytes)
+		variable := f.VariableByName(name)
+
+		if variable == nil {
+			return errors.New(&errors.UnknownIdentifier{Name: name}, f.File, left.Token.Position)
+		}
+
+		defer f.UseVariable(variable)
+		return f.Execute(comparison.Token, variable.Register, right)
+	}
+
+	if ast.IsFunctionCall(left) && right.IsLeaf() {
+		_, err := f.CompileCall(left)
+
+		if err != nil {
+			return err
+		}
+
+		return f.ExecuteLeaf(comparison.Token, f.CPU.Output[0], right.Token)
+	}
+
+	tmp := f.NewRegister()
+	_, err := f.ExpressionToRegister(left, tmp)
+
+	if err != nil {
+		return err
+	}
+
+	defer f.FreeRegister(tmp)
+	return f.Execute(comparison.Token, tmp, right)
+}