GH#8 - preserve newlines when collapsing whitespace

When we collapse a series of whitespace characters, *if* that series of
characters happens to contain a newline character in it then we will
collapse *to* a newline character.

That way, we don't accidentally break "semi-colons are optional in
JavaScript" by collapsing multiple statements onto a single line.

Author: bleargh45

Changes

@@ -1,6 +1,9 @@
 Revision history for Perl extension JavaScript::Minifier::XS.
 
 {{$NEXT}}
+    - GH#8 - preserve newlines when collapsing whitespace; if a block of
+      whitespace contains a newline, then when collapsing we collapse to a
+      newline character, not just "the first whitespace char we found"
 
 0.14      2021-02-06 23:36:36-08:00 America/Vancouver
     - rewrote test suite into a single ".t" test

XS.xs

@@ -283,7 +283,21 @@ void JsAppendNode(Node* element, Node* node) {
 /* collapses a node to a single whitespace character */
 void JsCollapseNodeToWhitespace(Node* node) {
     if (node->contents && (node->length > 1)) {
+        /* does the node contain endspace? */
+        size_t offset = 0;
+        bool hasEndspace = 0;
+        while (offset < node->length) {
+          if (charIsEndspace(node->contents[offset++])) {
+            hasEndspace = 1;
+            break;
+          }
+        }
+
+        /* collapse node, either to endspace, or to the first whitespace char */
         node->length = 1;
+        if (hasEndspace) {
+          node->contents[0] = '\n';
+        }
         node->contents[1] = '\0';
     }
 }

t/minify.t

@@ -21,6 +21,14 @@ subtest 'trailing whitespace can be removed' => sub {
   is $got, $expect;
 };
 
+###############################################################################
+subtest 'whitespace collapsing preserves newlines' => sub {
+  my $given  = qq{var a=3   \n\rvar a=5};
+  my $expect = qq{var a=3\nvar a=5};
+  my $got    = minify($given);
+  is $got, $expect;
+};
+
 ###############################################################################
 subtest 'comments' => sub {;
   subtest 'block comments' => sub {