Move fmt

compiler/fmt/src/spaces.rs

@@ -0,0 +1,115 @@
+use bumpalo::collections::String;
+use roc_parse::ast::CommentOrNewline;
+
+/// The number of spaces to indent.
+pub const INDENT: u16 = 4;
+
+pub fn newline<'a>(buf: &mut String<'a>, indent: u16) {
+    buf.push('\n');
+
+    add_spaces(buf, indent);
+}
+
+pub fn add_spaces<'a>(buf: &mut String<'a>, spaces: u16) {
+    for _ in 0..spaces {
+        buf.push(' ');
+    }
+}
+
+pub fn fmt_spaces<'a, I>(buf: &mut String<'a>, spaces: I, indent: u16)
+where
+    I: Iterator<Item = &'a CommentOrNewline<'a>>,
+{
+    use self::CommentOrNewline::*;
+
+    // Only ever print two newlines back to back.
+    // (Two newlines renders as one blank line.)
+    let mut consecutive_newlines = 0;
+    let mut iter = spaces.peekable();
+
+    let mut encountered_comment = false;
+
+    while let Some(space) = iter.next() {
+        match space {
+            Newline => {
+                if !encountered_comment && (consecutive_newlines < 2) {
+                    if iter.peek() == Some(&&Newline) {
+                        buf.push('\n');
+                    } else {
+                        newline(buf, indent);
+                    }
+
+                    // Don't bother incrementing it if we're already over the limit.
+                    // There's no upside, and it might eventually overflow,
+                    consecutive_newlines += 1;
+                }
+            }
+            LineComment(comment) => {
+                fmt_comment(buf, comment, indent);
+
+                encountered_comment = true;
+            }
+        }
+    }
+}
+
+/// Similar to fmt_comments_only, but does not finish with a newline()
+/// Used to format when and if statement conditions
+pub fn fmt_condition_spaces<'a, I>(buf: &mut String<'a>, spaces: I, indent: u16)
+where
+    I: Iterator<Item = &'a CommentOrNewline<'a>>,
+{
+    use self::CommentOrNewline::*;
+
+    let mut iter = spaces.peekable();
+
+    while let Some(space) = iter.next() {
+        match space {
+            Newline => {}
+            LineComment(comment) => {
+                buf.push('#');
+                buf.push_str(comment);
+            }
+        }
+        match iter.peek() {
+            None => {}
+            Some(next_space) => match next_space {
+                Newline => {}
+                LineComment(_) => {
+                    newline(buf, indent);
+                }
+            },
+        }
+    }
+}
+
+/// Like format_spaces, but remove newlines and keep only comments.
+pub fn fmt_comments_only<'a, I>(buf: &mut String<'a>, spaces: I, indent: u16)
+where
+    I: Iterator<Item = &'a CommentOrNewline<'a>>,
+{
+    use self::CommentOrNewline::*;
+
+    for space in spaces {
+        match space {
+            Newline => {}
+            LineComment(comment) => {
+                fmt_comment(buf, comment, indent);
+            }
+        }
+    }
+}
+
+fn fmt_comment<'a>(buf: &mut String<'a>, comment: &'a str, indent: u16) {
+    buf.push('#');
+    buf.push_str(comment);
+
+    newline(buf, indent);
+}
+
+pub fn is_comment<'a>(space: &'a CommentOrNewline<'a>) -> bool {
+    match space {
+        CommentOrNewline::Newline => false,
+        CommentOrNewline::LineComment(_) => true,
+    }
+}