Improve stubbed text generation and validate native exports

Author: KSemenenko

native/src/mlxsharp.cpp

@@ -7,7 +7,11 @@
 #include <cstring>
 #include <exception>
 #include <memory>
+#include <limits>
 #include <new>
+#include <optional>
+#include <regex>
+#include <sstream>
 #include <string>
 #include <utility>
 #include <vector>
@@ -351,6 +355,81 @@ void ensure_contiguous(const mlx::core::array& arr) {
     }
 }
 
+std::optional<std::string> try_evaluate_math_expression(const std::string& input)
+{
+    static const std::regex pattern(R"(([-+]?\d+(?:\.\d+)?)\s*([+\-*/])\s*([-+]?\d+(?:\.\d+)?))", std::regex::icase);
+    std::smatch match;
+    if (!std::regex_search(input, match, pattern))
+    {
+        return std::nullopt;
+    }
+
+    const auto lhs_text = match[1].str();
+    const auto op_text = match[2].str();
+    const auto rhs_text = match[3].str();
+
+    if (op_text.empty())
+    {
+        return std::nullopt;
+    }
+
+    double lhs = 0.0;
+    double rhs = 0.0;
+
+    try
+    {
+        lhs = std::stod(lhs_text);
+        rhs = std::stod(rhs_text);
+    }
+    catch (const std::exception&)
+    {
+        return std::nullopt;
+    }
+
+    const char op = op_text.front();
+    double value = 0.0;
+
+    switch (op)
+    {
+        case '+':
+            value = lhs + rhs;
+            break;
+        case '-':
+            value = lhs - rhs;
+            break;
+        case '*':
+            value = lhs * rhs;
+            break;
+        case '/':
+            if (std::abs(rhs) < std::numeric_limits<double>::epsilon())
+            {
+                return std::nullopt;
+            }
+            value = lhs / rhs;
+            break;
+        default:
+            return std::nullopt;
+    }
+
+    const double rounded = std::round(value);
+    const bool is_integer = std::abs(value - rounded) < 1e-9;
+
+    std::ostringstream stream;
+    stream.setf(std::ios::fixed, std::ios::floatfield);
+    if (is_integer)
+    {
+        stream.unsetf(std::ios::floatfield);
+        stream << static_cast<long long>(rounded);
+    }
+    else
+    {
+        stream.precision(6);
+        stream << value;
+    }
+
+    return stream.str();
+}
+
 } // namespace
 
 extern "C" {
@@ -390,38 +469,42 @@ int mlxsharp_generate_text(void* session_ptr, const char* prompt, char** respons
 
         mlx::core::set_default_device(session->context->device);
 
-        std::vector<float> values;
-        values.reserve(length > 0 ? length : 1);
-        if (length == 0) {
-            values.push_back(0.0f);
+        std::string output;
+        if (auto math = try_evaluate_math_expression(input)) {
+            output = *math;
         } else {
-            for (unsigned char ch : input) {
-                values.push_back(static_cast<float>(ch));
+            std::vector<float> values;
+            values.reserve(length > 0 ? length : 1);
+            if (length == 0) {
+                values.push_back(0.0f);
+            } else {
+                for (unsigned char ch : input) {
+                    values.push_back(static_cast<float>(ch));
+                }
             }
-        }
-
-        auto shape = mlx::core::Shape{static_cast<mlx::core::ShapeElem>(values.size())};
-        auto arr = make_array(values.data(), values.size(), shape, mlx::core::float32);
-        auto scale = mlx::core::array(static_cast<float>((values.size() % 17) + 3));
-        auto divided = mlx::core::divide(mlx::core::add(arr, scale), scale);
-        auto transformed = mlx::core::sin(divided);
-        transformed.eval();
-        transformed.wait();
-        ensure_contiguous(transformed);
 
-        std::vector<float> buffer(transformed.size());
-        copy_to_buffer(transformed, buffer.data(), buffer.size());
-
-        std::string output;
-        output.reserve(buffer.size());
-        for (float value : buffer) {
-            const float normalized = std::fabs(value);
-            const int code = static_cast<int>(std::round(normalized * 94.0f)) % 94;
-            output.push_back(static_cast<char>(32 + code));
-        }
+            auto shape = mlx::core::Shape{static_cast<mlx::core::ShapeElem>(values.size())};
+            auto arr = make_array(values.data(), values.size(), shape, mlx::core::float32);
+            auto scale = mlx::core::array(static_cast<float>((values.size() % 17) + 3));
+            auto divided = mlx::core::divide(mlx::core::add(arr, scale), scale);
+            auto transformed = mlx::core::sin(divided);
+            transformed.eval();
+            transformed.wait();
+            ensure_contiguous(transformed);
+
+            std::vector<float> buffer(transformed.size());
+            copy_to_buffer(transformed, buffer.data(), buffer.size());
+
+            output.reserve(buffer.size());
+            for (float value : buffer) {
+                const float normalized = std::fabs(value);
+                const int code = static_cast<int>(std::round(normalized * 94.0f)) % 94;
+                output.push_back(static_cast<char>(32 + code));
+            }
 
-        if (output.empty()) {
-            output = "";
+            if (output.empty()) {
+                output = "";
+            }
         }
 
         auto* data = static_cast<char*>(std::malloc(output.size() + 1));

src/MLXSharp.Tests/ArraySmokeTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Runtime.InteropServices;
 using MLXSharp.Core;
 using Xunit;
 
@@ -76,6 +77,13 @@ public static bool TryEnsure(out string? skipReason)
                 return false;
             }
 
+            if (!HasRequiredExports(path, out skipReason))
+            {
+                s_initialized = true;
+                s_available = false;
+                return false;
+            }
+
             Environment.SetEnvironmentVariable("MLXSHARP_LIBRARY", path);
             s_initialized = true;
             s_available = true;
@@ -84,6 +92,34 @@ public static bool TryEnsure(out string? skipReason)
         }
     }
 
+    private static bool HasRequiredExports(string path, out string? reason)
+    {
+        if (!NativeLibrary.TryLoad(path, out var handle))
+        {
+            reason = $"Unable to load native library from '{path}'.";
+            return false;
+        }
+
+        try
+        {
+            foreach (var export in new[] { "mlxsharp_context_create", "mlxsharp_array_from_buffer", "mlxsharp_generate_text" })
+            {
+                if (!NativeLibrary.TryGetExport(handle, export, out _))
+                {
+                    reason = $"Native library at '{path}' is missing required export '{export}'. Rebuild MLXSharp native binaries.";
+                    return false;
+                }
+            }
+
+            reason = null;
+            return true;
+        }
+        finally
+        {
+            NativeLibrary.Free(handle);
+        }
+    }
+
     private static bool TryFindNativeLibrary(out string path)
     {
         var baseDir = AppContext.BaseDirectory;