gn format: use input line breaks rather than attempting rule-based line breaks

I couldn't come up with anything that worked in 100% of cases, so switch
to mostly maintaining line breaks from input file instead.

R=brettw@chromium.org
BUG=348474

Review URL: https://codereview.chromium.org/713463003

Cr-Commit-Position: refs/heads/master@{#303313}

8 files changed, 35 insertions, 12 deletions

diff --git a/tools/gn/command_format.cc b/tools/gn/command_format.cc
index a72e2ec3..890cf2c 100644
--- a/tools/gn/command_format.cc
+++ b/tools/gn/command_format.cc
@@ -242,16 +242,11 @@ bool Printer::IsAssignment(const ParseNode* node) {
 
 bool Printer::ShouldAddBlankLineInBetween(const ParseNode* a,
                                           const ParseNode* b) {
-  if ((IsAssignment(a) || a->AsFunctionCall()) &&
-      (!a->comments() || a->comments()->after().size() == 0) &&
-      (IsAssignment(b) || b->AsFunctionCall()) &&
-      (!b->comments() || b->comments()->before().size() == 0)) {
-    Metrics first = GetLengthOfExpr(a, kPrecedenceLowest);
-    Metrics second = GetLengthOfExpr(b, kPrecedenceLowest);
-    if (!first.multiline || !second.multiline)
-      return false;
-  }
-  return true;
+  LocationRange a_range = a->GetRange();
+  LocationRange b_range = b->GetRange();
+  // If they're already separated by 1 or more lines, then we want to keep a
+  // blank line.
+  return b_range.begin().line_number() > a_range.end().line_number() + 1;
 }
 
 int Printer::CurrentColumn() {
diff --git a/tools/gn/command_format_unittest.cc b/tools/gn/command_format_unittest.cc
index 31bc4be..6458179 100644
--- a/tools/gn/command_format_unittest.cc
+++ b/tools/gn/command_format_unittest.cc
@@ -70,8 +70,9 @@ FORMAT_TEST(031)
 FORMAT_TEST(033)
 // TODO(scottmg): args+rebase_path unnecessarily split: FORMAT_TEST(034)
 FORMAT_TEST(035)
-// TODO(scottmg): Line breaks between early statements: FORMAT_TEST(036)
+FORMAT_TEST(036)
 // TODO(scottmg): Ugly line breaking: FORMAT_TEST(037)
 FORMAT_TEST(038)
 // TODO(scottmg): Bad break, exceeding 80 col: FORMAT_TEST(039)
 // TODO(scottmg): Bad break, exceeding 80 col: FORMAT_TEST(040)
+FORMAT_TEST(041)
diff --git a/tools/gn/format_test_data/003.golden b/tools/gn/format_test_data/003.golden
index 5084c0f..a5bd5d3 100644
--- a/tools/gn/format_test_data/003.golden
+++ b/tools/gn/format_test_data/003.golden
@@ -3,5 +3,6 @@ executable("test") {
     "stuff.cc",
     "things.cc",
   ]
+
   deps = [ "//base" ]
 }
diff --git a/tools/gn/format_test_data/017.golden b/tools/gn/format_test_data/017.golden
index 4e84a50..d9d7ad9 100644
--- a/tools/gn/format_test_data/017.golden
+++ b/tools/gn/format_test_data/017.golden
@@ -3,10 +3,10 @@ executable("win"  # Suffix comment on arg.
            # And a strangely positioned line comment for some reason
            ) {
   defines = []  # Defines comment, suffix at end position.
+
   deps = [
     # Deps comment, should be forced multiline.
   ]
-
   sources = [
     "a.cc",
     # End of single sources comment, should be forced multiline.
diff --git a/tools/gn/format_test_data/021.golden b/tools/gn/format_test_data/021.golden
index 3919f49..40d8c78 100644
--- a/tools/gn/format_test_data/021.golden
+++ b/tools/gn/format_test_data/021.golden
@@ -1,9 +1,12 @@
 f(aaaaaaaaaaaaaaaaaaa)
+
 f(aaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaa)
 
 # Exactly 80 wide.
 f(aaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaa, aaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaa, aaaaa)
+
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)
+
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)
 
diff --git a/tools/gn/format_test_data/028.golden b/tools/gn/format_test_data/028.golden
index d22d4a2..a1d54c5 100644
--- a/tools/gn/format_test_data/028.golden
+++ b/tools/gn/format_test_data/028.golden
@@ -1,5 +1,7 @@
 # Don't separate these.
 import("wee.gni")
 import("waa.gni")
+
 import("woo.gni")
+
 import("blah.gni")
diff --git a/tools/gn/format_test_data/036.golden b/tools/gn/format_test_data/036.golden
new file mode 100644
index 0000000..5a5eca84
--- /dev/null
+++ b/tools/gn/format_test_data/036.golden
@@ -0,0 +1,9 @@
+import("a")
+import("b")
+
+assert(x)
+assert(y)
+assert(z)
+
+source_set("stuff") {
+}
diff --git a/tools/gn/format_test_data/041.golden b/tools/gn/format_test_data/041.golden
new file mode 100644
index 0000000..fa39b49
--- /dev/null
+++ b/tools/gn/format_test_data/041.golden
@@ -0,0 +1,12 @@
+if (true) {
+  a = [ "wee" ]
+
+  b = [
+    "x",
+    "y",
+    "z",
+  ]
+  c = [ "x" ]
+
+  d = [ "x" ]
+}