150 lines
3.9 KiB
Rust
150 lines
3.9 KiB
Rust
/*
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Module: char
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Utilities for manipulating the char type
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*/
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/*
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Function: is_whitespace
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Indicates whether a character is whitespace.
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Whitespace characters include space (U+0020), tab (U+0009), line feed
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(U+000A), carriage return (U+000D), and a number of less common
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ASCII and unicode characters.
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*/
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pure fn is_whitespace(c: char) -> bool {
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const ch_space: char = '\u0020';
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const ch_ogham_space_mark: char = '\u1680';
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const ch_mongolian_vowel_sep: char = '\u180e';
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const ch_en_quad: char = '\u2000';
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const ch_em_quad: char = '\u2001';
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const ch_en_space: char = '\u2002';
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const ch_em_space: char = '\u2003';
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const ch_three_per_em_space: char = '\u2004';
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const ch_four_per_em_space: char = '\u2005';
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const ch_six_per_em_space: char = '\u2006';
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const ch_figure_space: char = '\u2007';
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const ch_punctuation_space: char = '\u2008';
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const ch_thin_space: char = '\u2009';
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const ch_hair_space: char = '\u200a';
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const ch_narrow_no_break_space: char = '\u202f';
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const ch_medium_mathematical_space: char = '\u205f';
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const ch_ideographic_space: char = '\u3000';
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const ch_line_separator: char = '\u2028';
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const ch_paragraph_separator: char = '\u2029';
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const ch_character_tabulation: char = '\u0009';
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const ch_line_feed: char = '\u000a';
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const ch_line_tabulation: char = '\u000b';
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const ch_form_feed: char = '\u000c';
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const ch_carriage_return: char = '\u000d';
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const ch_next_line: char = '\u0085';
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const ch_no_break_space: char = '\u00a0';
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if c == ch_space {
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true
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} else if c == ch_ogham_space_mark {
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true
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} else if c == ch_mongolian_vowel_sep {
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true
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} else if c == ch_en_quad {
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true
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} else if c == ch_em_quad {
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true
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} else if c == ch_en_space {
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true
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} else if c == ch_em_space {
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true
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} else if c == ch_three_per_em_space {
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true
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} else if c == ch_four_per_em_space {
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true
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} else if c == ch_six_per_em_space {
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true
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} else if c == ch_figure_space {
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true
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} else if c == ch_punctuation_space {
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true
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} else if c == ch_thin_space {
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true
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} else if c == ch_hair_space {
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true
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} else if c == ch_narrow_no_break_space {
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true
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} else if c == ch_medium_mathematical_space {
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true
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} else if c == ch_ideographic_space {
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true
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} else if c == ch_line_tabulation {
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true
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} else if c == ch_paragraph_separator {
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true
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} else if c == ch_character_tabulation {
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true
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} else if c == ch_line_feed {
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true
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} else if c == ch_line_tabulation {
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true
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} else if c == ch_form_feed {
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true
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} else if c == ch_carriage_return {
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true
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} else if c == ch_next_line {
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true
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} else if c == ch_no_break_space { true } else { false }
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}
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/*
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Function: to_digit
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Convert a char to the corresponding digit.
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Parameters:
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c - a char, either '0' to '9', 'a' to 'z' or 'A' to 'Z'
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Returns:
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If `c` is between '0' and '9', the corresponding value between 0 and 9.
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If `c` is 'a' or 'A', 10. If `c` is 'b' or 'B', 11, etc.
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Safety note:
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This function fails if `c` is not a valid char
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*/
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pure fn to_digit(c: char) -> u8 unsafe {
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alt maybe_digit(c) {
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option::some(x) { x }
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option::none. { fail; }
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}
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}
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/*
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Function: to_digit
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Convert a char to the corresponding digit. Returns none when the
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character is not a valid hexadecimal digit.
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*/
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pure fn maybe_digit(c: char) -> option::t<u8> {
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alt c {
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'0' to '9' { option::some(c as u8 - ('0' as u8)) }
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'a' to 'z' { option::some(c as u8 + 10u8 - ('a' as u8)) }
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'A' to 'Z' { option::some(c as u8 + 10u8 - ('A' as u8)) }
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_ { option::none }
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}
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}
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/*
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Function: cmp
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Compare two chars.
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Parameters:
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a - a char
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b - a char
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Returns:
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-1 if a<b, 0 if a==b, +1 if a>b
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*/
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pure fn cmp(a: char, b: char) -> int {
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ret if b > a { -1 }
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else if b < a { 1 }
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else { 0 }
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} |