coreutils/fmt/parasplit.rs

532 lines
20 KiB
Rust

/*
* This file is part of `fmt` from the uutils coreutils package.
*
* (c) kwantam <kwantam@gmail.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
use core::iter::Peekable;
use std::io::Lines;
use std::slice::Items;
use std::str::CharRange;
use FileOrStdReader;
use FmtOptions;
// lines with PSKIP, lacking PREFIX, or which are entirely blank are
// NoFormatLines; otherwise, they are FormatLines
#[deriving(Show)]
enum Line {
FormatLine(FileLine),
NoFormatLine(String, bool)
}
impl Line {
// when we know that it's a FormatLine, as in the ParagraphStream iterator
fn get_fileline(self) -> FileLine {
match self {
FormatLine(fl) => fl,
NoFormatLine(..) => fail!("Found NoFormatLine when expecting FormatLine")
}
}
// when we know that it's a NoFormatLine, as in the ParagraphStream iterator
fn get_noformatline(self) -> (String, bool) {
match self {
NoFormatLine(s, b) => (s, b),
FormatLine(..) => fail!("Found FormatLine when expecting NoFormatLine")
}
}
}
// each line's prefix has to be considered to know whether to merge it with
// the next line or not
#[deriving(Show)]
struct FileLine {
line : String,
indent_end : uint, // the end of the indent, always the start of the text
prefix_end : uint, // the end of the PREFIX
pfxind_end : uint, // the end of the PREFIX's indent, that is, the spaces before the prefix
indent_len : uint, // display length of indent taking into account TABWIDTH
pfxind_len : uint, // PREFIX indent length taking into account TABWIDTH
}
// iterator that produces a stream of Lines from a file
struct FileLines<'a> {
opts : &'a FmtOptions,
lines : Lines<'a, FileOrStdReader>,
}
impl<'a> FileLines<'a> {
fn new<'a>(opts: &'a FmtOptions, lines: Lines<'a, FileOrStdReader>) -> FileLines<'a> {
FileLines { opts: opts, lines: lines }
}
// returns true if this line should be formatted
fn match_prefix(&self, line: &str) -> (bool, uint) {
if !self.opts.use_prefix { return (true, 0u); }
FileLines::match_prefix_generic(self.opts.prefix.as_slice(), line, self.opts.xprefix)
}
// returns true if this line should be formatted
fn match_anti_prefix(&self, line: &str) -> bool {
if !self.opts.use_anti_prefix { return true; }
match FileLines::match_prefix_generic(self.opts.anti_prefix.as_slice(), line, self.opts.xanti_prefix) {
(true, _) => false,
(_ , _) => true
}
}
fn match_prefix_generic(pfx: &str, line: &str, exact: bool) -> (bool, uint) {
if line.starts_with(pfx) {
return (true, 0);
}
if !exact {
// we do it this way rather than byte indexing to support unicode whitespace chars
let mut i = 0u;
while (i < line.len()) && line.char_at(i).is_whitespace() {
i = match line.char_range_at(i) { CharRange { ch: _ , next: nxi } => nxi };
if line.slice_from(i).starts_with(pfx) {
return (true, i);
}
}
}
(false, 0)
}
fn displayed_length(&self, s: &str) -> uint {
s.char_len() + (self.opts.tabwidth - 1) * s.chars().filter(|x| x == &'\t').count()
}
}
impl<'a> Iterator<Line> for FileLines<'a> {
fn next(&mut self) -> Option<Line> {
let mut n =
match self.lines.next() {
Some(t) => match t {
Ok(tt) => tt,
Err(_) => return None
},
None => return None
};
// if this line is entirely whitespace,
// emit a blank line
// Err(true) indicates that this was a linebreak,
// which is important to know when detecting mail headers
if n.as_slice().is_whitespace() {
return Some(NoFormatLine("\n".to_string(), true));
}
// if this line does not match the prefix,
// emit the line unprocessed and iterate again
let (pmatch, poffset) = self.match_prefix(n.as_slice());
if !pmatch {
return Some(NoFormatLine(n, false));
}
// if this line matches the anti_prefix
// (NOTE definition of match_anti_prefix is TRUE if we should process)
if !self.match_anti_prefix(n.as_slice()) {
return Some(NoFormatLine(n, false));
}
// replace trailing newline, if any, with space
let CharRange {ch, next: i} = n.as_slice().char_range_at_reverse(n.len());
if ch == '\n' {
unsafe {
let nmut = n.as_mut_bytes();
nmut[i] = ' ' as u8;
}
if i > 0 {
let CharRange {ch, next: _} = n.as_slice().char_range_at_reverse(i);
if ch == '.' {
n.push_char(' ');
}
}
}
let nLen = n.len();
// figure out the indent, prefix, and prefixindent ending points
let (indEnd, pfxEnd, pfxIndEnd) =
if self.opts.use_prefix {
let pfxEnd = poffset + self.opts.prefix.len();
let nSlice = n.as_slice().slice_from(pfxEnd);
let nSlice2 = nSlice.trim_left();
(pfxEnd + nSlice.len() - nSlice2.len(), pfxEnd, poffset)
} else {
let nSlice = n.as_slice().trim_left();
(nLen - nSlice.len(), 0, 0)
};
// indent length
let indLen =
if indEnd > 0 {
self.displayed_length(n.as_slice().slice(pfxEnd, indEnd))
} else {
0
};
// prefix indent length
let pfxIndLen =
if pfxIndEnd > 0 {
self.displayed_length(n.as_slice().slice_to(pfxIndEnd))
} else {
0
};
// if we are in uniform mode, all tabs after the indent should be replaced by spaces.
// NOTE that in this implementation, [?!.]\t is NOT detected as a sentence break, but
// [?!.]\t\t is. We could expand tabs to two spaces to force detection of tab as
// sentence ending
if self.opts.uniform {
let tabinds: Vec<uint> = n.as_slice().slice_from(indEnd).char_indices().filter_map(|(i, c)| if c == '\t' { Some(i) } else { None }).collect();
unsafe {
let nmut = n.as_mut_bytes();
for i in tabinds.iter() {
nmut[*i] = ' ' as u8;
}
}
}
Some(FormatLine(FileLine {
line : n,
indent_end : indEnd,
prefix_end : pfxEnd,
pfxind_end : pfxIndEnd,
indent_len : indLen,
pfxind_len : pfxIndLen,
}))
}
}
// a paragraph : a collection of FileLines that are to be formatted
// plus info about the paragraph's indentation
// (but we only retain the String from the FileLine; the other info
// is only there to help us in deciding how to merge lines into Paragraphs
#[deriving(Show)]
pub struct Paragraph {
lines : Vec<String>, // the lines of the file
pub init_str : String, // string representing the init, that is, the first line's indent
pub init_len : uint, // printable length of the init string considering TABWIDTH
init_end : uint, // byte location of end of init in first line String
pub indent_str : String, // string representing indent
pub indent_len : uint, // length of above
indent_end : uint, // byte location of end of indent (in crown and tagged mode, only applies to 2nd line and onward)
pub pfxind_str : String, // string representing the prefix indent
pub pfxind_len : uint, // length of above
pub mail_header : bool // we need to know if this is a mail header because we do word splitting differently in that case
}
// an iterator producing a stream of paragraphs from a stream of lines
// given a set of options.
// NOTE as you iterate through the paragraphs, any NoFormatLines are
// immediately dumped to stdout!
pub struct ParagraphStream<'a> {
lines : Peekable<Line,FileLines<'a>>,
next_mail : bool,
opts : &'a FmtOptions,
}
impl<'a> ParagraphStream<'a> {
pub fn new<'a>(opts: &'a FmtOptions, reader: &'a mut FileOrStdReader) -> ParagraphStream<'a> {
let lines = FileLines::new(opts, reader.lines()).peekable();
// at the beginning of the file, we might find mail headers
ParagraphStream { lines: lines, next_mail: true, opts: opts }
}
// detect RFC822 mail header
fn is_mail_header(line: &FileLine) -> bool {
// a mail header begins with either "From " (envelope sender line)
// or with a sequence of printable ASCII chars (33 to 126, inclusive,
// except colon) followed by a colon.
if line.indent_end > 0 {
false
} else {
let lSlice = line.line.as_slice();
if lSlice.starts_with("From ") {
true
} else {
let colonPosn =
match lSlice.find(':') {
Some(n) => n,
None => return false
};
// header field must be nonzero length
if colonPosn == 0 { return false; }
return lSlice.slice_to(colonPosn).chars().all(|x| match x as uint {
y if y < 33 || y > 126 => false,
_ => true
});
}
}
}
}
impl<'a> Iterator<Result<Paragraph,String>> for ParagraphStream<'a> {
fn next(&mut self) -> Option<Result<Paragraph,String>> {
// return a NoFormatLine in an Err; it should immediately be output
let noformat =
match self.lines.peek() {
None => return None,
Some(l) => match l {
&FormatLine(_) => false,
&NoFormatLine(_, _) => true
}
};
// found a NoFormatLine, immediately dump it out
if noformat {
let (s, nm) = self.lines.next().unwrap().get_noformatline();
self.next_mail = nm;
return Some(Err(s));
}
// found a FormatLine, now build a paragraph
let mut init_str = String::new();
let mut init_end = 0;
let mut init_len = 0;
let mut indent_str = String::new();
let mut indent_end = 0;
let mut indent_len = 0;
let mut pfxind_str = String::new();
let mut pfxind_len = 0;
let mut pLines = Vec::new();
let mut in_mail = false;
let mut second_done = false; // for when we use crown or tagged mode
loop {
{ // peek ahead
// need to explicitly force fl out of scope before we can call self.lines.next()
let fl =
match self.lines.peek() {
None => break,
Some(l) => {
match l {
&FormatLine(ref x) => x,
&NoFormatLine(..) => break
}
}
};
if pLines.len() == 0 {
// first time through the loop, get things set up
// detect mail header
if self.opts.mail && self.next_mail && ParagraphStream::is_mail_header(fl) {
in_mail = true;
// there can't be any indent or pfxind because otherwise is_mail_header would fail
// since there cannot be any whitespace before the colon in a valid header field
indent_str.push_str(" ");
indent_len = 2;
} else {
if self.opts.crown || self.opts.tagged {
init_str.push_str(fl.line.as_slice().slice_to(fl.indent_end));
init_len = fl.indent_len + fl.pfxind_len + self.opts.prefix_len;
init_end = fl.indent_end;
}
// these will be overwritten in the 2nd line of crown or tagged mode, but
// we are not guaranteed to get to the 2nd line, e.g., if the next line
// is a NoFormatLine or None. Thus, we set sane defaults the 1st time around
indent_str.push_str(fl.line.as_slice().slice(fl.prefix_end, fl.indent_end));
indent_len = fl.indent_len;
indent_end = fl.indent_end;
// in tagged mode, add 4 spaces of additional indenting by default
// (gnu fmt's behavior is different: it seems to find the closest column to
// indent_end that is divisible by 3. But honesly that behavior seems
// pretty arbitrary.
// Perhaps a better default would be 1 TABWIDTH? But ugh that's so big.
if self.opts.tagged {
indent_str.push_str(" ");
indent_len += 4;
}
if self.opts.use_prefix {
pfxind_str.push_str(fl.line.as_slice().slice_to(fl.pfxind_end));
pfxind_len = fl.pfxind_len;
}
}
} else if in_mail {
// lines following mail headers must begin with spaces
if (self.opts.use_prefix && fl.pfxind_end == 0) || (!self.opts.use_prefix && fl.indent_end == 0) {
break; // this line does not begin with spaces
}
} else if !second_done && (self.opts.crown || self.opts.tagged) {
// now we have enough info to handle crown margin and tagged mode
if pfxind_len != fl.pfxind_len {
// in both crown and tagged modes we require that pfxind is the same
break;
} else if self.opts.tagged && (indent_end == fl.indent_end) {
// in tagged mode, indent also has to be different
break;
} else {
// this is part of the same paragraph, get the indent info from this line
indent_str.clear();
indent_str.push_str(fl.line.as_slice().slice(fl.prefix_end, fl.indent_end));
indent_len = fl.indent_len;
indent_end = fl.indent_end;
}
second_done = true;
} else {
// detect mismatch
if (indent_end != fl.indent_end) || (indent_len != fl.indent_len) || (pfxind_len != fl.pfxind_len) {
break;
}
}
}
pLines.push(self.lines.next().unwrap().get_fileline().line);
// when we're in split-only mode, we never join lines, so stop here
if self.opts.split_only {
break;
}
}
// if this was a mail header, then the next line can be detected as one. Otherwise, it cannot.
// NOTE next_mail is true at ParagraphStream instantiation, and is set to true after a blank
// NoFormatLine.
self.next_mail = in_mail;
Some(Ok(Paragraph {
lines : pLines,
init_str : init_str,
init_len : init_len,
init_end : init_end,
indent_str : indent_str,
indent_len : indent_len,
indent_end : indent_end,
pfxind_str : pfxind_str,
pfxind_len : pfxind_len,
mail_header : in_mail
}))
}
}
pub struct ParaWords<'a> {
opts : &'a FmtOptions,
para : &'a Paragraph,
words : Vec<&'a str>
}
impl<'a> ParaWords<'a> {
pub fn new<'a>(opts: &'a FmtOptions, para: &'a Paragraph) -> ParaWords<'a> {
let mut pw = ParaWords { opts: opts, para: para, words: Vec::new() };
pw.create_words();
pw
}
fn create_words<'r>(&'r mut self) {
if self.para.mail_header {
// no extra spacing for mail headers; always exactly 1 space
// safe to trim_left on every line of a mail header, since the
// first line is guaranteed not to have any spaces
self.words.push_all_move(self.para.lines.iter().flat_map(|x| x.as_slice().trim_left().words()).collect());
} else {
// first line
self.words.push_all_move(
if self.opts.crown || self.opts.tagged {
// crown and tagged mode has the "init" in the first line, so slice from there
WordSplit::new(self.opts.uniform, self.para.lines.get(0).as_slice().slice_from(self.para.init_end))
} else {
// otherwise we slice from the indent
WordSplit::new(self.opts.uniform, self.para.lines.get(0).as_slice().slice_from(self.para.indent_end))
}.collect());
if self.para.lines.len() > 1 {
let indent_end = self.para.indent_end;
let uniform = self.opts.uniform;
self.words.push_all_move(
self.para.lines.iter().skip(1)
.flat_map(|x| WordSplit::new(uniform, x.as_slice().slice_from(indent_end)))
.collect());
}
}
}
pub fn words(&'a self) -> Items<'a,&'a str> { return self.words.iter() }
}
struct WordSplit<'a> {
uniform : bool,
string : &'a str,
length : uint,
position : uint
}
impl<'a> WordSplit<'a> {
fn new<'a>(uniform: bool, string: &'a str) -> WordSplit<'a> {
// wordsplits *must* start at a non-whitespace character
let trim_string = string.trim_left();
WordSplit { uniform: uniform, string: trim_string, length: string.len(), position: 0 }
}
fn is_punctuation(c: char) -> bool {
match c {
'!' | '.' | '?' => true,
_ => false
}
}
}
impl<'a> Iterator<&'a str> for WordSplit<'a> {
fn next(&mut self) -> Option<&'a str> {
if self.position >= self.length {
return None
}
let old_position = self.position;
// find the start of the next whitespace segment
let ws_start =
match self.string.slice_from(old_position).find(|x: char| x.is_whitespace()) {
None => self.length,
Some(s) => s + old_position
};
if ws_start == self.length {
self.position = self.length;
return Some(self.string.slice_from(old_position));
}
// find the end of the next whitespace segment
// note that this preserves the invariant that self.position points to
// non-whitespace character OR end of string
self.position =
match self.string.slice_from(ws_start).find(|x: char| !x.is_whitespace()) {
None => self.length,
Some(s) => s + ws_start
};
let is_sentence_end = match self.string.char_range_at_reverse(ws_start) {
CharRange { ch, next: _ } if WordSplit::is_punctuation(ch) => self.position - ws_start > 2,
_ => false
};
Some(
if self.uniform {
// if the last non-whitespace character is a [?!.] and
// there are two or more spaces, this is the end of a
// sentence, so keep one extra space.
if is_sentence_end {
self.string.slice(old_position, ws_start + 1)
} else {
self.string.slice(old_position, ws_start)
}
} else {
// in non-uniform mode, we just keep the whole thing
// eventually we will want to annotate where the sentence boundaries are
// so that we can give preference to splitting lines appropriately
self.string.slice(old_position, self.position)
}
)
}
}