Improved branch compilation

src/build/core/Compare.go

@@ -0,0 +1,47 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/build/ast"
+	"git.akyoto.dev/cli/q/src/build/errors"
+	"git.akyoto.dev/cli/q/src/build/expression"
+	"git.akyoto.dev/cli/q/src/build/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()
+		variable, exists := f.variables[name]
+
+		if !exists {
+			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.Execute(comparison.Token, f.cpu.Output[0], right)
+	}
+
+	tmp := f.cpu.MustFindFree(f.cpu.General)
+	err := f.ExpressionToRegister(left, tmp)
+
+	if err != nil {
+		return err
+	}
+
+	f.cpu.Use(tmp)
+	defer f.cpu.Free(tmp)
+	return f.Execute(comparison.Token, tmp, right)
+}