accept comments before the header

compiler/parse/src/header.rs

@@ -71,6 +71,7 @@ pub struct InterfaceHeader<'a> {
     pub imports: Vec<'a, Loc<ImportsEntry<'a>>>,
 
     // Potential comments and newlines - these will typically all be empty.
+    pub before_header: &'a [CommentOrNewline<'a>],
     pub after_interface_keyword: &'a [CommentOrNewline<'a>],
     pub before_exposes: &'a [CommentOrNewline<'a>],
     pub after_exposes: &'a [CommentOrNewline<'a>],
@@ -93,6 +94,7 @@ pub struct AppHeader<'a> {
     pub to: Loc<To<'a>>,
 
     // Potential comments and newlines - these will typically all be empty.
+    pub before_header: &'a [CommentOrNewline<'a>],
     pub after_app_keyword: &'a [CommentOrNewline<'a>],
     pub before_packages: &'a [CommentOrNewline<'a>],
     pub after_packages: &'a [CommentOrNewline<'a>],
@@ -112,6 +114,7 @@ pub struct PackageHeader<'a> {
     pub imports: Vec<'a, Loc<ImportsEntry<'a>>>,
 
     // Potential comments and newlines - these will typically all be empty.
+    pub before_header: &'a [CommentOrNewline<'a>],
     pub after_package_keyword: &'a [CommentOrNewline<'a>],
     pub before_exposes: &'a [CommentOrNewline<'a>],
     pub after_exposes: &'a [CommentOrNewline<'a>],
@@ -132,6 +135,7 @@ pub struct PlatformHeader<'a> {
     pub effects: Effects<'a>,
 
     // Potential comments and newlines - these will typically all be empty.
+    pub before_header: &'a [CommentOrNewline<'a>],
     pub after_platform_keyword: &'a [CommentOrNewline<'a>],
     pub before_requires: &'a [CommentOrNewline<'a>],
     pub after_requires: &'a [CommentOrNewline<'a>],

compiler/parse/src/module.rs

@@ -57,16 +57,37 @@ fn header<'a>() -> impl Parser<'a, Module<'a>, EHeader<'a>> {
 
     one_of![
         map!(
-            skip_first!(keyword_e("app", EHeader::Start), app_header()),
+            and!(
-            |header| { Module::App { header } }
+                space0_e(0, EHeader::Space, EHeader::IndentStart),
+                skip_first!(keyword_e("app", EHeader::Start), app_header())
+            ),
+            |(spaces, mut header): (&'a [CommentOrNewline], AppHeader<'a>)| {
+                header.before_header = spaces;
+
+                Module::App { header }
+            }
         ),
         map!(
-            skip_first!(keyword_e("platform", EHeader::Start), platform_header()),
+            and!(
-            |header| { Module::Platform { header } }
+                space0_e(0, EHeader::Space, EHeader::IndentStart),
+                skip_first!(keyword_e("platform", EHeader::Start), platform_header())
+            ),
+            |(spaces, mut header): (&'a [CommentOrNewline], PlatformHeader<'a>)| {
+                header.before_header = spaces;
+
+                Module::Platform { header }
+            }
         ),
         map!(
-            skip_first!(keyword_e("interface", EHeader::Start), interface_header()),
+            and!(
-            |header| { Module::Interface { header } }
+                space0_e(0, EHeader::Space, EHeader::IndentStart),
+                skip_first!(keyword_e("interface", EHeader::Start), interface_header())
+            ),
+            |(spaces, mut header): (&'a [CommentOrNewline], InterfaceHeader<'a>)| {
+                header.before_header = spaces;
+
+                Module::Interface { header }
+            }
         )
     ]
 }
@@ -89,6 +110,7 @@ fn interface_header<'a>() -> impl Parser<'a, InterfaceHeader<'a>, EHeader<'a>> {
             name,
             exposes,
             imports,
+            before_header: &[] as &[_],
             after_interface_keyword,
             before_exposes,
             after_exposes,
@@ -210,6 +232,7 @@ fn app_header<'a>() -> impl Parser<'a, AppHeader<'a>, EHeader<'a>> {
             imports,
             provides: provides.entries,
             to: provides.to,
+            before_header: &[] as &[_],
             after_app_keyword,
             before_packages,
             after_packages,
@@ -259,6 +282,7 @@ fn platform_header<'a>() -> impl Parser<'a, PlatformHeader<'a>, EHeader<'a>> {
             imports,
             provides,
             effects,
+            before_header: &[] as &[_],
             after_platform_keyword,
             before_requires,
             after_requires,