zls/src/translate_c.zig

const std = @import("std");
const builtin = @import("builtin");
const Config = @import("Config.zig");
const ast = @import("ast.zig");
const Ast = std.zig.Ast;
const URI = @import("uri.zig");

/// converts a `@cInclude` node into an equivalent c header file
/// which can then be handed over to `zig translate-c`
/// Caller owns returned memory.
///
/// **Example**
/// ```zig
/// const glfw = @cImport(
///     @cDefine("GLFW_INCLUDE_VULKAN", {})
///     @cInclude("GLFW/glfw3.h")
/// );
/// ```
/// gets converted into:
/// ```c
/// #define GLFW_INCLUDE_VULKAN
/// #include "GLFW/glfw3.h"
/// ```
pub fn convertCInclude(allocator: std.mem.Allocator, tree: Ast, node: Ast.Node.Index) error{ OutOfMemory, Unsupported }![]const u8 {
    const main_tokens = tree.nodes.items(.main_token);

    std.debug.assert(ast.isBuiltinCall(tree, node));
    std.debug.assert(std.mem.eql(u8, Ast.tokenSlice(tree, main_tokens[node]), "@cImport"));

    var output = std.ArrayList(u8).init(allocator);
    errdefer output.deinit();

    var stack_allocator = std.heap.stackFallback(512, allocator);

    var buffer: [2]Ast.Node.Index = undefined;
    for (ast.builtinCallParams(tree, node, &buffer).?) |child| {
        try convertCIncludeInternal(stack_allocator.get(), tree, child, &output);
    }

    return output.toOwnedSlice();
}

fn convertCIncludeInternal(allocator: std.mem.Allocator, tree: Ast, node: Ast.Node.Index, output: *std.ArrayList(u8)) error{ OutOfMemory, Unsupported }!void {
    const node_tags = tree.nodes.items(.tag);
    const main_tokens = tree.nodes.items(.main_token);

    var buffer: [2]Ast.Node.Index = undefined;
    if (ast.isBlock(tree, node)) {
        const FrameSize = @sizeOf(@Frame(convertCIncludeInternal));
        var child_frame = try allocator.alignedAlloc(u8, std.Target.stack_align, FrameSize);
        defer allocator.free(child_frame);

        for (ast.blockStatements(tree, node, &buffer).?) |statement| {
            try await @asyncCall(child_frame, {}, convertCIncludeInternal, .{ allocator, tree, statement, output });
        }
    } else if (ast.builtinCallParams(tree, node, &buffer)) |params| {
        if (params.len < 1) return;

        const call_name = Ast.tokenSlice(tree, main_tokens[node]);

        if (node_tags[params[0]] != .string_literal) return error.Unsupported;
        const first = extractString(Ast.tokenSlice(tree, main_tokens[params[0]]));

        if (std.mem.eql(u8, call_name, "@cInclude")) {
            try output.writer().print("#include <{s}>\n", .{first});
        } else if (std.mem.eql(u8, call_name, "@cDefine")) {
            if (params.len < 2) return;

            var buffer2: [2]Ast.Node.Index = undefined;
            const is_void = if (ast.blockStatements(tree, params[1], &buffer2)) |block| block.len == 0 else false;

            if (is_void) {
                try output.writer().print("#define {s}\n", .{first});
            } else {
                if (node_tags[params[1]] != .string_literal) return error.Unsupported;
                const second = extractString(Ast.tokenSlice(tree, main_tokens[params[1]]));
                try output.writer().print("#define {s} {s}\n", .{ first, second });
            }
        } else if (std.mem.eql(u8, call_name, "@cUndef")) {
            try output.writer().print("#undefine {s}\n", .{first});
        } else {
            return error.Unsupported;
        }
    }
}

/// takes a c header file and returns the result from calling `zig translate-c`
/// returns the file path to the generated zig file
/// Caller owns returned memory.
pub fn translate(allocator: std.mem.Allocator, config: Config, include_dirs: []const []const u8, source: []const u8) error{OutOfMemory}!?[]const u8 {
    const file_path = try std.fs.path.join(allocator, &[_][]const u8{ config.global_cache_path.?, "cimport.h" });
    defer allocator.free(file_path);

    var file = std.fs.createFileAbsolute(file_path, .{}) catch |err| {
        std.log.warn("failed to create file '{s}': {}", .{ file_path, err });
        return null;
    };
    defer file.close();
    defer std.fs.deleteFileAbsolute(file_path) catch |err| {
        std.log.warn("failed to delete file '{s}': {}", .{ file_path, err });
    };

    _ = file.write(source) catch |err| {
        std.log.warn("failed to write to '{s}': {}", .{ file_path, err });
    };

    const base_include_dirs = blk: {
        const target_info = std.zig.system.NativeTargetInfo.detect(allocator, .{}) catch break :blk null;
        var native_paths = std.zig.system.NativePaths.detect(allocator, target_info) catch break :blk null;
        defer native_paths.deinit();

        break :blk native_paths.include_dirs.toOwnedSlice();
    };
    defer if (base_include_dirs) |dirs| {
        for (dirs) |path| {
            allocator.free(path);
        }
        allocator.free(dirs);
    };

    const base_args = &[_][]const u8{
        config.zig_exe_path.?,
        "translate-c",
        "--enable-cache",
        "--zig-lib-dir",
        config.zig_lib_path.?,
        "--cache-dir",
        config.global_cache_path.?,
    };

    const argc = base_args.len + 2 * (include_dirs.len + if (base_include_dirs) |dirs| dirs.len else 0) + 1;
    var argv = try std.ArrayListUnmanaged([]const u8).initCapacity(allocator, argc);
    defer argv.deinit(allocator);

    argv.appendSliceAssumeCapacity(base_args);

    if (base_include_dirs) |dirs| {
        for (dirs) |include_dir| {
            argv.appendAssumeCapacity("-I");
            argv.appendAssumeCapacity(include_dir);
        }
    }

    for (include_dirs) |include_dir| {
        argv.appendAssumeCapacity("-I");
        argv.appendAssumeCapacity(include_dir);
    }

    argv.appendAssumeCapacity(file_path);

    const result = std.ChildProcess.exec(.{
        .allocator = allocator,
        .argv = argv.items,
    }) catch |err| {
        std.log.err("Failed to execute zig translate-c process, error: {}", .{err});
        return null;
    };

    defer allocator.free(result.stdout);
    defer allocator.free(result.stderr);

    return switch (result.term) {
        .Exited => |code| if (code == 0) {
            return try std.mem.join(allocator, "", &.{
                "file://",
                std.mem.sliceTo(result.stdout, '\n'),
            });
        } else {
            // TODO convert failure to `textDocument/publishDiagnostics`
            std.log.err("zig translate-c process failed, code: {}, stderr: '{s}'", .{ code, result.stderr });
            return null;
        },
        else => {
            std.log.err("zig translate-c process terminated '{}'", .{result.term});
            return null;
        },
    };
}

fn extractString(str: []const u8) []const u8 {
    if (std.mem.startsWith(u8, str, "\"") and std.mem.endsWith(u8, str, "\"")) {
        return str[1 .. str.len - 1];
    } else {
        return str;
    }
}