utils: source map generator

Author: krishpranav

src/utils/source_map_generator.cr

@@ -25,21 +25,89 @@ module MoonScript
 
     getter sources_content = [] of String
 
-    getter sources_names = [] of String
+    getter source_names = [] of String
 
     getter sources = [] of String
 
-    def initialize(unsorted: Deque(Mapping), @generated)
-        unsorted.each do |item|
-            (mappings[item[1][0]] ||= [] of Mapping) << item
-        end
+    getter generated : String
+
+    def initialize(unsorted : Deque(Mapping), @generated)
+      unsorted.each do |item|
+        (mappings[item[1][0]] ||= [] of Mapping) << item
+      end
     end
 
     def get_source_index(file)
-        sources.index(file.path) || begin
-            sources_content << file.contents
-            sources << file.path
-            sources.size - 1 
+      sources.index(file.path) || begin
+        sources_content << file.contents
+        sources << file.path
+        sources.size - 1
+      end
+    end
+
+    def get_source_name_index(value)
+      source_names.index(value) || begin
+        source_names << value
+        source_names.size - 1
+      end
+    end
+
+    def generate : String
+      last_name_index = 0
+      last_column = 0
+      last_index = 0
+      last_line = 0
+
+      generated_mappings =
+        (0..generated.lines.size).map do |line_index|
+          next "" unless items = mappings[line_index]?
+
+          items.reduce({[] of String, 0}) do |(memo, last), item|
+            column =
+              item[1][1]
+
+            segment =
+              VLQ.encode(column - last)
+
+            if node = item[0]
+              source_line =
+                node.from.line - 1
+
+              source_column =
+                node.from.column
+
+              source_index =
+                get_source_index(node.file)
+
+              segment += VLQ.encode(source_index - last_index)
+              segment += VLQ.encode(source_line - last_line)
+              segment += VLQ.encode(source_column - last_column)
+
+              if name = item[2]
+                source_name_index =
+                  get_source_name_index(name)
+
+                segment += VLQ.encode(source_name_index - last_name_index)
+                last_name_index = source_name_index
+              end
+
+              last_column = source_column
+              last_index = source_index
+              last_line = source_line
+            end
+
+            memo << segment
+            {memo, column}
+          end.first.join(",")
+        end.join(";")
+
+      {
+        mappings:       generated_mappings,
+        sourcesContent: sources_content,
+        names:          source_names,
+        sources:        sources,
+        version:        3,
+      }.to_json
     end
   end
 end