fish_indent: Collapse successive newlines

This makes it so code like

```fish
echo foo

echo bar
```

is collapsed into

```fish
echo foo

echo bar
```

One empty line is allowed, more is overkill.

We could also allow more than one for e.g. function endings.

Author: faho

src/bin/fish_indent.rs

@@ -127,7 +127,8 @@ impl<'source, 'ast> PrettyPrinter<'source, 'ast> {
                 },
                 output: WString::default(),
                 current_indent: 0,
-                gap_text_mask_newline: false,
+                // Start with true to ignore leading empty lines.
+                gap_text_mask_newline: true,
                 gaps: vec![],
                 preferred_semi_locations: vec![],
                 errors: None,
@@ -430,15 +431,16 @@ impl<'source, 'ast> PrettyPrinterState<'source, 'ast> {
             if needs_nl {
                 self.emit_newline();
                 needs_nl = false;
+                self.gap_text_mask_newline = false;
                 if tok_text == "\n" {
                     continue;
                 }
             } else if self.gap_text_mask_newline {
-                // We only respect mask_newline the first time through the loop.
-                self.gap_text_mask_newline = false;
-                if tok_text == "\n" {
+                // When told to mask newlines, we do it as long as we get semicolon or newline.
+                if tok.type_ == TokenType::end {
                     continue;
                 }
+                self.gap_text_mask_newline = false;
             }
 
             if tok.type_ == TokenType::comment {
@@ -451,6 +453,8 @@ impl<'source, 'ast> PrettyPrinterState<'source, 'ast> {
                 // Newlines are preserved unless mask_newline is set.
                 if tok_text == "\n" {
                     self.emit_newline();
+                    // Ignore successive ends.
+                    self.gap_text_mask_newline = true;
                 }
             } else {
                 // Anything else we write a space.
@@ -620,11 +624,6 @@ impl<'source, 'ast> PrettyPrinterState<'source, 'ast> {
             } else {
                 self.emit_newline();
             }
-
-            // If it was a semi but we emitted a newline, swallow a subsequent newline.
-            if !prefer_semi && self.substr(range) == ";" {
-                self.gap_text_mask_newline = true;
-            }
         }
     }
 

tests/checks/indent.fish

@@ -74,7 +74,6 @@ end | cat | cat | begin ; echo hi ; end | begin ; begin ; echo hi ; end ; end ar
 #CHECK: begin
 #CHECK: {{    }}echo hi
 #CHECK: 
-#CHECK: 
 #CHECK: end | cat | cat | begin
 #CHECK: {{    }}echo hi
 #CHECK: end | begin
@@ -96,10 +95,8 @@ end
 ' | $fish_indent
 
 #CHECK: switch aloha
-#CHECK: 
 #CHECK: {{    }}case alpha
 #CHECK: {{    }}{{    }}echo sup
-#CHECK: 
 #CHECK: {{    }}case beta gamma
 #CHECK: {{    }}{{    }}echo hi
 #CHECK: 
@@ -150,7 +147,6 @@ qqq
    case "*"
        echo sup
 end' | $fish_indent
-#CHECK: 
 #CHECK: echo alpha #comment1
 #CHECK: #comment2
 #CHECK: 
@@ -324,7 +320,6 @@ echo bye
 #CHECK: end
 #CHECK: 
 #CHECK: echo hi |
-#CHECK: 
 #CHECK: {{    }}echo bye
 
 echo 'a;;;;;;' | $fish_indent
@@ -449,3 +444,23 @@ echo "\'\\\\\x00\'" | string unescape | $fish_indent | string escape
 
 echo '\"\"\|\x00' | string unescape | $fish_indent | string unescape
 # CHECK: |
+
+echo 'a
+
+
+;
+
+
+b
+' | $fish_indent
+#CHECK: a
+#CHECK:
+#CHECK: b
+
+echo "
+
+
+
+echo this file starts late
+" | $fish_indent
+#CHECK: echo this file starts late