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//! Reformat's Haskell's whitespace to use explicit braces and semicolons.
use trans::{encode_literal};
use regex::{Captures, Regex};
// TODO rename "strip comments and other stuff too i guess"
fn strip_comments(text: &str) -> String {
// Strip comments
let re = Regex::new(r"\{-[\s\S]*?-\}").unwrap();
let text = re.replace_all(&text, "").to_string();
// To prevent double dashes in quotation marks, we trivially ignore quotes
// that immediately follow the comment.
// TODO find a better way to do this
let re = Regex::new(r#"--[^\n\r"][^\n\r]*"#).unwrap();
let text = re.replace_all(&text, "").to_string();
let re = Regex::new(r#"--([\n\r])"#).unwrap();
let text = re.replace_all(&text, "$1").to_string();
// Strip trailing semicolons (so we don't have "empty statements")
let re = Regex::new(r"(?m);+\s*$").unwrap();
let text = re.replace_all(&text, "").to_string();
// Strip preprocessor decls
let re = Regex::new(r"(?m)^#(if|ifn?def|endif|else|include|elif).*").unwrap();
let text = re.replace_all(&text, "").to_string();
// TODO this should be handled in the parser
let escape_re = Regex::new(r#"\\([abfnrtv'"\\0]|NUL|ESC)"#).unwrap();
let decode_escapes = |text: &str| {
let text = escape_re.replace_all(text, |caps: &Captures| {
match &caps[1] {
"a" => "\u{0007}",
"b" => "\u{0008}",
"f" => "\u{000C}",
"n" => "\n",
"r" => "\r",
"t" => "\t",
"v" => "\u{000B}",
"'" => "'",
"\"" => "\"",
"\\" => "\\",
"0" | "NUL" => "\0",
"ESC" => "\x1b",
s => panic!("str escape {}", s),
}.into()
});
text.to_string()
};
// Char literals.
let re = Regex::new(r"'([^'\\]|\\[A-Z]{1,3}|\\.)'").unwrap();
let text = re.replace_all(&text, |caps: &Captures| {
let v = decode_escapes(&caps[1]);
assert!(v.len() == 1, "multi char literal {:?}", v);
format!("'{}'", encode_literal(&v))
}).to_string();
// Replace all strings with an encoded version to make the parser simpler.
// If its possible to get LALRPOP to not complain with proper string regexes, should just use
// that instead
let re = Regex::new(r#""(([^"\\]|\\.)*?)""#).unwrap();
let text = re.replace_all(&text, |caps: &Captures| {
let v = decode_escapes(&caps[1]);
format!("\"{}\"", encode_literal(&v))
}).to_string();
// Convert forall a b. to forall a b; for simpler parsing
let re = Regex::new(r"forall\s+(.*?)\.").unwrap();
let text = re.replace_all(&text, "forall $1;").to_string();
text
}
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
enum BlockWord {
Do,
Where,
Of,
Let,
In,
If,
Then,
Else,
}
impl BlockWord {
fn from_str(word: &str) -> Option<Self> {
use self::BlockWord::*;
Some(match word {
"do" => Do,
"where" => Where,
"of" => Of,
"let" => Let,
"in" => In,
"if" => If,
"then" => Then,
"else" => Else,
_ => return None,
})
}
}
/// Convert indentation to semicolon-delimited brackets, so it can be parsed more easily.
pub fn commify(val: &str) -> String {
let re_space = Regex::new(r#"^[ \t]+"#).unwrap();
let re_nl = Regex::new(r#"^\r?\n"#).unwrap();
let re_word = Regex::new(r#"([\(\{\[\]\}\)]|[^ \t\r\n\(\{\[\]\}\)]+)"#).unwrap();
// Strip out all comments from the contents.
let commentless = strip_comments(val);
// Previous indentation levels
let mut stash: Vec<(usize, BlockWord)> = vec![];
// Previously popped from `stash`.
let mut popped: Option<(usize, BlockWord)> = None;
// Previous brace nesting levels.
let mut braces: Vec<isize> = vec![];
// Previous word was a block starting word.
let mut trigger: Option<(BlockWord, usize)> = None;
// How many spaces to indent.
let mut indent = 0;
// Check if this is the first word in the line.
let mut first = true;
// Check if this is the first word after an in statement.
let mut in_active = false;
let mut out = String::new();
let mut v: &str = &commentless;
while v.len() > 0 {
if let Some(cap) = re_space.captures(v) {
let word = &cap[0];
out.push_str(word);
v = &v[word.len()..];
indent += word.len();
} else if let Some(cap) = re_nl.captures(v) {
let word = &cap[0];
out.push_str(word);
v = &v[word.len()..];
indent = 0;
first = true;
if stash.len() > 1 {
for _ in &stash[1..] {
out.push_str(" ");
}
}
} else if let Some(cap) = re_word.captures(v) {
let word = &cap[0];
macro_rules! pop_brace {
() => ({
popped = stash.pop();
braces.pop();
out.push_str("}");
});
}
// TODO why do we need to prevent `;} then` semicolon insertion here
if first && word != "then" {
while {
if let Some(&(last_level, last_word)) = stash.last() {
// Check if we decreased our indent level
last_level > indent
|| (last_level == indent && word == "where")
} else {
false
}
} {
// out.push_str(&format!("[{:?}]", stash.last()));
pop_brace!();
}
if let Some(&(i, _)) = stash.last() {
if i == indent && trigger.is_none() {
out.push_str(";");
}
}
}
if ["]", ")", "}"].contains(&word) {
if let Some(brace) = braces.last_mut() {
*brace -= 1;
}
}
if ["[", "(", "{"].contains(&word) {
if let Some(brace) = braces.last_mut() {
*brace += 1;
}
}
// End braces insertion when meeting an unbalanced ending ), }, or ]
while {
if let Some(brace) = braces.last().map(|x| *x) {
brace < 0
} else {
false
}
} {
pop_brace!();
if braces.len() > 0 {
*braces.last_mut().unwrap() -= 1;
}
}
// make sure `let { ... } in` is closed
if word == "in" && !first {
// are we still in the `let`?
if let Some(&(_, BlockWord::Let)) = stash.last() {
pop_brace!();
} else if let Some((_, BlockWord::Let)) = popped {
// a `let { ... }` just closed so we don't have to do anything
} else {
let bw = stash.last().expect("`in` at top level").1;
out.push_str(&format!(" /* ERR: `in` while in `{:?}` block */ ", bw));
}
}
// make sure `if { ... } then` is closed
if word == "then" {
// are we still in the `if`?
if let Some(&(_, BlockWord::If)) = stash.last() {
pop_brace!();
} else if let Some((_, BlockWord::If)) = popped {
// an `If { ... }` just closed so we don't have to do anything
} else {
let bw = stash.last().expect("`if` at top level").1;
out.push_str(&format!(" /* ERR: `ifin` while in `{:?}` block */ ", bw));
}
}
out.push_str(word);
v = &v[word.len()..];
if let Some((block_word, trigger_indent)) = trigger {
// The next word after a block word is where the whitespace column begins.
if first || block_word != BlockWord::In {
stash.push((indent, block_word));
} else {
stash.push((trigger_indent, block_word));
}
}
first = false;
trigger = BlockWord::from_str(word).map(|x| (x, indent));
if trigger.is_some() {
out.push_str("{");
// Trace brace indentation level.
braces.push(0);
}
indent += word.len();
} else {
unreachable!("unknown prop {:?}", v);
}
}
for _ in 0..stash.len() {
out.push_str("}");
}
// Replace trailing commas after where statements
// TODO fix this in the parser instead
let re = Regex::new(r#"where\s+;"#).unwrap();
let out = re.replace_all(&out, r#"where "#).to_string();
// let re = Regex::new(r#"\};\s*where\b"#).unwrap();
// let out = re.replace_all(&out, r#"} where"#).to_string();
let re = Regex::new(r#"\};\}"#).unwrap();
let out = re.replace_all(&out, r#"}}"#).to_string();
out
}