refactor command functions

examples/chorus.scri

@@ -1,3 +1,3 @@
 load :0;
-chorus 3 1 3 10 0.5 1 9 0;
+chorus 3 1 3 10 0.01 0.1 2 0;
 quicksave;

src/runner.zig

@@ -3,6 +3,9 @@ const lang = @import("lang.zig");
 const images = @import("image.zig");
 const plugin = @import("plugin.zig");
 
+const Position = plugin.Position;
+const ParamList = plugin.ParamList;
+
 const Image = images.Image;
 
 pub const RunError = error{
@@ -11,10 +14,6 @@ pub const RunError = error{
     ImageRequired,
 };
 
-fn appendParam(params: *plugin.ParamList, sym: []const u8, value: f32) !void {
-    try params.append(plugin.Param{ .sym = sym, .value = value });
-}
-
 pub const Runner = struct {
     allocator: *std.mem.Allocator,
     image: ?*Image = null,
@@ -154,95 +153,41 @@ pub const Runner = struct {
     }
 
     /// Run the http://lv2plug.in/plugins/eg-amp plugin over the file.
-    fn ampCmd(self: *Runner, split: usize, index: usize, gain: f32) !void {
+    fn ampCmd(self: *Runner, pos: Position, params: ParamList) !void {
         var image = try self.getImage();
-
-        var params = plugin.ParamList.init(self.allocator);
-        defer params.deinit();
-
-        try params.append(plugin.Param{ .sym = "gain", .value = gain });
-
-        // TODO if we could detect that the next command is a quicksave then
-        // we don't need the temporary file in runPlugin and instead we
-        // dump it all on the output image for it.
-        try image.runPlugin(
-            "http://lv2plug.in/plugins/eg-amp",
-            plugin.Position{ .split = split, .index = index },
-            params,
-        );
+        try image.runPlugin("http://lv2plug.in/plugins/eg-amp", pos, params);
     }
 
-    fn rFlangerCmd(
-        self: *Runner,
-        split: usize,
-        index: usize,
-        delay_depth_avg: f32,
-        law_freq: f32,
-    ) !void {
+    fn rFlangerCmd(self: *Runner, pos: Position, params: ParamList) !void {
         var image = try self.getImage();
-        var params = plugin.ParamList.init(self.allocator);
-        defer params.deinit();
-
-        try params.append(plugin.Param{ .sym = "delay_depth_avg", .value = delay_depth_avg });
-        try params.append(plugin.Param{ .sym = "law_freq", .value = law_freq });
-
-        try image.runPlugin(
-            "http://plugin.org.uk/swh-plugins/retroFlange",
-            plugin.Position{ .split = split, .index = index },
-            params,
-        );
+        try image.runPlugin("http://plugin.org.uk/swh-plugins/retroFlange", pos, params);
     }
 
-    fn eqCmd(
-        self: *Runner,
-        position: plugin.Position,
-        lo: f32,
-        mid: f32,
-        high: f32,
-    ) !void {
+    fn eqCmd(self: *Runner, position: Position, params: ParamList) !void {
         var image = try self.getImage();
-        var params = plugin.ParamList.init(self.allocator);
-        defer params.deinit();
-
-        try appendParam(&params, "lo", lo);
-        try appendParam(&params, "mid", mid);
-        try appendParam(&params, "hi", high);
-
         try image.runPlugin("http://plugin.org.uk/swh-plugins/dj_eq_mono", position, params);
     }
 
-    fn phaserCmd(
-        self: *Runner,
-        position: plugin.Position,
-        lfo_rate: f32,
-        lfo_depth: f32,
-        fb: f32,
-        spread: f32,
-    ) !void {
+    fn phaserCmd(self: *Runner, position: Position, params: ParamList) !void {
         var image = try self.getImage();
-        var params = plugin.ParamList.init(self.allocator);
-        defer params.deinit();
-
-        try appendParam(&params, "lfo_rate", lfo_rate);
-        try appendParam(&params, "lfo_depth", lfo_depth);
-        try appendParam(&params, "fb", fb);
-        try appendParam(&params, "spread", spread);
-
         try image.runPlugin("http://plugin.org.uk/swh-plugins/lfoPhaser", position, params);
     }
 
     fn mbeqCmd(
         self: *Runner,
-        position: plugin.Position,
+        position: Position,
         bands: []const f32,
     ) !void {
         var image = try self.getImage();
-        var params = plugin.ParamList.init(self.allocator);
+        var params = ParamList.init(self.allocator);
         defer params.deinit();
 
         for (bands) |band_value, idx| {
             var sym = try std.fmt.allocPrint(self.allocator, "band_{}", idx + 1);
-            try appendParam(&params, sym, band_value);
+            try params.append(plugin.Param{
+                .sym = sym,
+                .value = band_value,
+            });
         }
 
         try image.runPlugin("http://plugin.org.uk/swh-plugins/mbeq", position, params);
@@ -250,15 +195,15 @@ pub const Runner = struct {
 
     fn chorusCmd(
         self: *Runner,
-        pos: plugin.Position,
-        params: plugin.ParamList,
+        pos: Position,
+        params: ParamList,
     ) !void {
         var image = try self.getImage();
         try image.runPlugin("http://plugin.org.uk/swh-plugins/multivoiceChorus", pos, params);
     }
 
     fn runCommand(self: *Runner, cmd: *lang.Command) !void {
-        var params = plugin.ParamList.init(self.allocator);
+        var params = ParamList.init(self.allocator);
         defer params.deinit();
 
         return switch (cmd.command) {
@@ -271,40 +216,36 @@ pub const Runner = struct {
             .Quicksave => try self.quicksaveCmd(),
 
             .Amp => blk: {
-                const split = try cmd.usizeArgAt(0);
-                const index = try cmd.usizeArgAt(1);
-                const gain = try cmd.floatArgAt(2);
-                try self.ampCmd(split, index, gain);
+                const pos = try cmd.consumePosition();
+                try cmd.appendParam(&params, "gain", 2);
+                try self.ampCmd(pos, params);
             },
 
             .RFlanger => blk: {
-                const split = try cmd.usizeArgAt(0);
-                const index = try cmd.usizeArgAt(1);
-                const delay_depth_avg = try cmd.floatArgAt(2);
-                const law_freq = try cmd.floatArgAt(3);
-
-                try self.rFlangerCmd(split, index, delay_depth_avg, law_freq);
+                const pos = try cmd.consumePosition();
+                try cmd.appendParam(&params, "delay_depth_avg", 2);
+                try cmd.appendParam(&params, "law_freq", 3);
+                try self.rFlangerCmd(pos, params);
             },
 
             .Eq => blk: {
                 const pos = try cmd.consumePosition();
+                try cmd.appendParam(&params, "lo", 2);
+                try cmd.appendParam(&params, "mid", 3);
+                try cmd.appendParam(&params, "hi", 4);
 
-                const lo = try cmd.floatArgAt(2);
-                const mid = try cmd.floatArgAt(3);
-                const high = try cmd.floatArgAt(4);
-
-                try self.eqCmd(pos, lo, mid, high);
+                try self.eqCmd(pos, params);
             },
 
             .Phaser => blk: {
                 const pos = try cmd.consumePosition();
 
-                const lfo_rate = try cmd.floatArgAt(2);
-                const lfo_depth = try cmd.floatArgAt(3);
-                const fb = try cmd.floatArgAt(4);
-                const spread = try cmd.floatArgAt(5);
+                try cmd.appendParam(&params, "lfo_rate", 2);
+                try cmd.appendParam(&params, "lfo_depth", 3);
+                try cmd.appendParam(&params, "fb", 4);
+                try cmd.appendParam(&params, "spread", 5);
 
-                try self.phaserCmd(pos, lfo_rate, lfo_depth, fb, spread);
+                try self.phaserCmd(pos, params);
             },
 
             .Mbeq => blk: {