Add basic Lemon parser generator support.

scripts/tundra/syntax/lemon.lua

@@ -0,0 +1,27 @@
+-- lemon.lua - Support for the Lemon parser generator
+
+module(..., package.seeall)
+
+local path     = require "tundra.path"
+
+DefRule {
+  Name = "Lemon",
+  Command = "lemon $(<)",
+  ConfigInvariant = true,
+
+  Blueprint = {
+    Source = { Required = true, Type = "string" },
+  },
+
+  Setup = function (env, data)
+    local src = data.Source
+    local base_name = path.drop_suffix(src)
+    local gen_c = base_name .. '.c'
+    local gen_h = base_name .. '.h'
+    local gen_out = base_name .. '.out'
+    return {
+      InputFiles = { src },
+      OutputFiles = { gen_c, gen_h, gen_out },
+    }
+  end,
+}