util.rs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#[deriving(Eq)]
pub enum CompressionMode {
    CompressNone,
    CompressWhitespace,
    CompressWhitespaceNewline,
    DiscardNewline
}

// ported from Gecko's nsTextFrameUtils::TransformText.
//
// High level TODOs:
//
// * Issue #113: consider incoming text state (arabic, etc)
//               and propogate outgoing text state (dual of above)
//
// * Issue #114: record skipped and kept chars for mapping original to new text
//
// * Untracked: various edge cases for bidi, CJK, etc.
pub fn transform_text(text: &str, mode: CompressionMode, incoming_whitespace: bool, new_line_pos: &mut Vec<uint>) -> (~str, bool) {
    let mut out_str: ~str = "".to_owned();
    let out_whitespace = match mode {
        CompressNone | DiscardNewline => {
            let mut new_line_index = 0;
            for ch in text.chars() {
                if is_discardable_char(ch, mode) {
                    // TODO: record skipped char
                } else {
                    // TODO: record kept char
                    if ch == '\t' {
                        // TODO: set "has tab" flag
                    } else if ch == '\n' {
                        // Save new-line's position for line-break
                        // This value is relative(not absolute)
                        new_line_pos.push(new_line_index);
                        new_line_index = 0;
                    }

                    if ch != '\n' {
                        new_line_index += 1;
                    }
                    out_str.push_char(ch);
                }
            }
            text.len() > 0 && is_in_whitespace(text.char_at_reverse(0), mode)
        },

        CompressWhitespace | CompressWhitespaceNewline => {
            let mut in_whitespace: bool = incoming_whitespace;
            for ch in text.chars() {
                // TODO: discard newlines between CJK chars
                let mut next_in_whitespace: bool = is_in_whitespace(ch, mode);

                if !next_in_whitespace {
                    if is_always_discardable_char(ch) {
                        // revert whitespace setting, since this char was discarded
                        next_in_whitespace = in_whitespace;
                        // TODO: record skipped char
                    } else {
                        // TODO: record kept char
                        out_str.push_char(ch);
                    }
                } else { /* next_in_whitespace; possibly add a space char */
                    if in_whitespace {
                        // TODO: record skipped char
                    } else {
                        // TODO: record kept char
                        out_str.push_char(' ');
                    }
                }
                // save whitespace context for next char
                in_whitespace = next_in_whitespace;
            } /* /for str::each_char */
            in_whitespace
        }
    };

    return (out_str, out_whitespace);

    fn is_in_whitespace(ch: char, mode: CompressionMode) -> bool {
        match (ch, mode) {
            (' ', _)  => true,
            ('\t', _) => true,
            ('\n', CompressWhitespaceNewline) => true,
            (_, _)    => false
        }
    }

    fn is_discardable_char(ch: char, mode: CompressionMode) -> bool {
        if is_always_discardable_char(ch) {
            return true;
        }
        match mode {
            DiscardNewline | CompressWhitespaceNewline => ch == '\n',
            _ => false
        }
    }

    fn is_always_discardable_char(_ch: char) -> bool {
        // TODO: check for bidi control chars, soft hyphens.
        false
    }
}

pub fn float_to_fixed(before: int, f: f64) -> i32 {
    (1i32 << before) * (f as i32)
}

pub fn fixed_to_float(before: int, f: i32) -> f64 {
    f as f64 * 1.0f64 / ((1i32 << before) as f64)
}

pub fn fixed_to_rounded_int(before: int, f: i32) -> int {
    let half = 1i32 << (before-1);
    if f > 0i32 {
        ((half + f) >> before) as int
    } else {
       -((half - f) >> before) as int
    }
}

/* Generate a 32-bit TrueType tag from its 4 characters */
pub fn true_type_tag(a: char, b: char, c: char, d: char) -> u32 {
    let a = a as u32;
    let b = b as u32;
    let c = c as u32;
    let d = d as u32;
    (a << 24 | b << 16 | c << 8 | d) as u32
}

#[test]
fn test_true_type_tag() {
    assert_eq!(true_type_tag('c', 'm', 'a', 'p'), 0x_63_6D_61_70_u32);
}

#[test]
fn test_transform_compress_none() {

    let  test_strs : ~[~str] = ~["  foo bar".to_owned(),
                                 "foo bar  ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 "  foo  bar  \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];
    let mode = CompressNone;

    for i in range(0, test_strs.len()) {
        let mut new_line_pos = vec!();
        let (trimmed_str, _out) = transform_text(test_strs[i], mode, true, &mut new_line_pos);
        assert_eq!(&trimmed_str, &test_strs[i])
    }
}

#[test]
fn test_transform_discard_newline() {

    let  test_strs : ~[~str] = ~["  foo bar".to_owned(),
                                 "foo bar  ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 "  foo  bar  \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];

    let  oracle_strs : ~[~str] = ~["  foo bar".to_owned(),
                                   "foo bar  ".to_owned(),
                                   "foo bar".to_owned(),
                                   "foo bar".to_owned(),
                                   "  foo  bar  baz".to_owned(),
                                   "foo bar baz".to_owned(),
                                   "foobarbaz".to_owned()];

    assert_eq!(test_strs.len(), oracle_strs.len());
    let mode = DiscardNewline;

    for i in range(0, test_strs.len()) {
        let mut new_line_pos = vec!();
        let (trimmed_str, _out) = transform_text(test_strs[i], mode, true, &mut new_line_pos);
        assert_eq!(&trimmed_str, &oracle_strs[i])
    }
}

/* FIXME: Fix and re-enable
#[test]
fn test_transform_compress_whitespace() {
    let  test_strs : ~[~str] = ~["  foo bar".to_owned(),
                                 "foo bar  ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 "  foo  bar  \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];

    let oracle_strs : ~[~str] = ~[" foo bar".to_owned(),
                                 "foo bar ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 " foo bar \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];

    assert_eq!(test_strs.len(), oracle_strs.len());
    let mode = CompressWhitespace;

    for i in range(0, test_strs.len()) {
        let mut new_line_pos = ~[];
        let (trimmed_str, _out) = transform_text(test_strs[i], mode, true, &mut new_line_pos);
        assert_eq!(&trimmed_str, &oracle_strs[i])
    }
}

#[test]
fn test_transform_compress_whitespace_newline() {
    let  test_strs : ~[~str] = ~["  foo bar".to_owned(),
                                 "foo bar  ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 "  foo  bar  \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];

    let oracle_strs : ~[~str] = ~["foo bar".to_owned(),
                                 "foo bar ".to_owned(),
                                 "foo bar".to_owned(),
                                 "foo bar".to_owned(),
                                 " foo bar baz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz ".to_owned()];

    assert_eq!(test_strs.len(), oracle_strs.len());
    let mode = CompressWhitespaceNewline;

    for i in range(0, test_strs.len()) {
        let mut new_line_pos = ~[];
        let (trimmed_str, _out) = transform_text(test_strs[i], mode, true, &mut new_line_pos);
        assert_eq!(&trimmed_str, &oracle_strs[i])
    }
}
*/

#[test]
fn test_transform_compress_whitespace_newline_no_incoming() {
    let  test_strs : ~[~str] = ~["  foo bar".to_owned(),
                                 "\nfoo bar".to_owned(),
                                 "foo bar  ".to_owned(),
                                 "foo\n bar".to_owned(),
                                 "foo \nbar".to_owned(),
                                 "  foo  bar  \nbaz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz\n\n".to_owned()];

    let oracle_strs : ~[~str] = ~[" foo bar".to_owned(),
                                 " foo bar".to_owned(),
                                 "foo bar ".to_owned(),
                                 "foo bar".to_owned(),
                                 "foo bar".to_owned(),
                                 " foo bar baz".to_owned(),
                                 "foo bar baz".to_owned(),
                                 "foobarbaz ".to_owned()];

    assert_eq!(test_strs.len(), oracle_strs.len());
    let mode = CompressWhitespaceNewline;

    for i in range(0, test_strs.len()) {
        let mut new_line_pos = vec!();
        let (trimmed_str, _out) = transform_text(test_strs[i], mode, false, &mut new_line_pos);
        assert_eq!(&trimmed_str, &oracle_strs[i])
    }
}