Added more tests

src/build/core/Evaluate.go

@@ -0,0 +1,41 @@
+package core
+
+import (
+	"git.akyoto.dev/cli/q/src/build/ast"
+	"git.akyoto.dev/cli/q/src/build/expression"
+	"git.akyoto.dev/cli/q/src/build/token"
+)
+
+// Evaluate evaluates an expression.
+func (f *Function) Evaluate(value *expression.Expression) error {
+	left := value.Children[0]
+	right := value.Children[1]
+
+	if left.IsLeaf() && left.Token.Kind == token.Identifier {
+		variable := f.variables[left.Token.Text()]
+		register := variable.Register
+		defer f.useVariable(variable)
+		return f.Execute(value.Token, register, right)
+	}
+
+	if ast.IsFunctionCall(left) && right.IsLeaf() {
+		err := f.CompileCall(left)
+
+		if err != nil {
+			return err
+		}
+
+		return f.Execute(value.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(value.Token, tmp, right)
+}