First CLI args usage

Author: der-teufel-programming

src/dim.zig

@@ -5,11 +5,73 @@ const std = @import("std");
 
 const Tokenizer = @import("Tokenizer.zig");
 const Parser = @import("Parser.zig");
+const args = @import("args");
+
+const Options = struct {
+    output: ?[]const u8 = null,
+    size: ?u32 = null,
+    script: ?[]const u8 = null,
+    @"import-env": bool = false,
+};
+
+const usage =
+    \\dim OPTIONS [VARS]
+    \\
+    \\OPTIONS:
+    \\ --output <path>
+    \\   mandatory: where to store the output file
+    \\[--size <size>]
+    \\   optional: how big is the resulting disk image? allowed suffixes: k,K,M,G
+    \\ --script <path>
+    \\   mandatory: which script file to execute?
+    \\[--import-env]
+    \\   optional: if set, imports the current process environment into the variables
+    \\VARS:
+    \\{ KEY=VALUE }*
+    \\  multiple ≥ 0: Sets variable KEY to VALUE
+    \\
+;
 
 pub fn main() !void {
+    var gpa_impl: std.heap.DebugAllocator(.{}) = .init;
+    defer _ = gpa_impl.deinit();
+
+    const gpa = gpa_impl.allocator();
+
+    const opts = try args.parseForCurrentProcess(Options, gpa, .print);
+    defer opts.deinit();
+
+    var var_map: std.StringArrayHashMapUnmanaged([]const u8) = .empty;
+    defer var_map.deinit(gpa);
 
-    //
+    for (opts.positionals) |pos| {
+        if (std.mem.indexOfScalar(u8, pos, '=')) |idx| {
+            const key = pos[0..idx];
+            const val = pos[idx + 1 ..];
+            try var_map.put(gpa, key, val);
+        }
+    }
+
+    const options = opts.options;
+
+    if (options.output == null) {
+        fatal("No output path specified");
+    }
+
+    if (options.script == null) {
+        fatal("No script specified");
+    }
+
+    std.debug.print(
+        "Output={?s} Script={?s} Size={?} import-env={}\n",
+        .{ options.output, options.script, options.size, options.@"import-env" },
+    );
+}
 
+fn fatal(msg: []const u8) noreturn {
+    std.debug.print("Error: {s}\n", .{msg});
+    std.debug.print("Usage: {s}", .{usage});
+    std.process.exit(1);
 }
 
 test {