Initialize the Prism::Source directly with all 3 fields for the C ext…

…ension

* Faster that way:
  $ ruby -Ilib -rprism -rbenchmark/ips -e 'Benchmark.ips { |x| x.report("parse") { Prism.parse("1 + 2") } }'
  195.722k (± 0.5%) i/s
  rb_iv_set():
  179.609k (± 0.5%) i/s
  rb_funcall():
  190.030k (± 0.3%) i/s
  before this PR:
  183.319k (± 0.4%) i/s

lib/prism/parse_result.rb

@@ -15,10 +15,10 @@ class Source
     attr_reader :offsets
 
     # Create a new source object with the given source code.
-    def initialize(source)
+    def initialize(source, start_line = 1, offsets = [])
       @source = source
-      @start_line = 1 # set after parsing is done
-      @offsets = [] # set after parsing is done
+      @start_line = start_line # set after parsing is done
+      @offsets = offsets # set after parsing is done
     end
 
     # Perform a byteslice on the source code using the given byte offset and

prism/extension.c

@@ -543,8 +543,9 @@ parse_lex_input(pm_string_t *input, const pm_options_t *options, bool return_nod
     pm_parser_register_encoding_changed_callback(&parser, parse_lex_encoding_changed_callback);
 
     VALUE source_string = rb_str_new((const char *) pm_string_source(input), pm_string_length(input));
-    VALUE source_argv[] = { source_string };
-    VALUE source = rb_class_new_instance(1, source_argv, rb_cPrismSource);
+    VALUE offsets = rb_ary_new();
+    VALUE source_argv[] = { source_string, LONG2NUM(parser.start_line), offsets };
+    VALUE source = rb_class_new_instance(3, source_argv, rb_cPrismSource);
 
     parse_lex_data_t parse_lex_data = {
         .source = source,
@@ -567,7 +568,10 @@ parse_lex_input(pm_string_t *input, const pm_options_t *options, bool return_nod
     // it over to all of the tokens, and both of these are only set after pm_parse().
     rb_encoding *encoding = rb_enc_find(parser.encoding->name);
     rb_enc_associate(source_string, encoding);
-    pm_source_init(source, &parser);
+
+    for (size_t index = 0; index < parser.newline_list.size; index++) {
+        rb_ary_push(offsets, ULONG2NUM(parser.newline_list.offsets[index]));
+    }
 
     VALUE value;
     if (return_nodes) {

prism/extension.h

@@ -8,7 +8,6 @@
 #include "prism.h"
 
 VALUE pm_source_new(pm_parser_t *parser, rb_encoding *encoding);
-void pm_source_init(VALUE source, pm_parser_t *parser);
 VALUE pm_token_new(pm_parser_t *parser, pm_token_t *token, rb_encoding *encoding, VALUE source);
 VALUE pm_ast_new(pm_parser_t *parser, pm_node_t *node, rb_encoding *encoding, VALUE source);
 

prism/templates/ext/prism/api_node.c.erb

@@ -40,22 +40,14 @@ pm_string_new(pm_string_t *string, rb_encoding *encoding) {
 VALUE
 pm_source_new(pm_parser_t *parser, rb_encoding *encoding) {
     VALUE source_string = rb_enc_str_new((const char *) parser->start, parser->end - parser->start, encoding);
-    VALUE source_argv[] = { source_string };
-    VALUE source = rb_class_new_instance(1, source_argv, rb_cPrismSource);
-
-    pm_source_init(source, parser);
-    return source;
-}
-
-void
-pm_source_init(VALUE source, pm_parser_t *parser) {
-    rb_iv_set(source, "@start_line", LONG2NUM(parser->start_line));
 
     VALUE offsets = rb_ary_new_capa(parser->newline_list.size);
     for (size_t index = 0; index < parser->newline_list.size; index++) {
         rb_ary_push(offsets, ULONG2NUM(parser->newline_list.offsets[index]));
     }
-    rb_iv_set(source, "@offsets", offsets);
+
+    VALUE source_argv[] = { source_string, LONG2NUM(parser->start_line), offsets };
+    return rb_class_new_instance(3, source_argv, rb_cPrismSource);
 }
 
 typedef struct pm_node_stack_node {

test/prism/parse_test.rb

@@ -52,6 +52,9 @@ def test_parse_takes_line
 
       assert_equal line, result.value.location.start_line
       assert_equal line + 1, find_source_file_node(result.value).location.start_line
+
+      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
+      assert_equal line, result.value.first.location.start_line
     end
 
     def test_parse_takes_negative_lines
@@ -60,6 +63,9 @@ def test_parse_takes_negative_lines
 
       assert_equal line, result.value.location.start_line
       assert_equal line + 1, find_source_file_node(result.value).location.start_line
+
+      result = Prism.parse_lex("def foo\n __FILE__\nend", line: line)
+      assert_equal line, result.value.first.location.start_line
     end
 
     def test_parse_lex