moc 0.19.2

Library made to create and manipulate HEALPix Multi-Order Coverages maps (MOCs), see https://ivoa.net/documents/MOC/
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254

//! Contains common method to parse FITS

use std::{
  io::{BufRead, Write},
  num::ParseIntError,
  slice::ChunksExact,
  str::{self, FromStr},
};

use quick_error::ResultExt;

use crate::deser::fits::error::FitsError;

const VALUE_INDICATOR: &[u8; 2] = b"= ";

pub(super) fn write_primary_hdu<R: Write>(writer: &mut R) -> Result<(), FitsError> {
  let mut header_block = [b' '; 2880];
  header_block[0..30].copy_from_slice(b"SIMPLE  =                    T");
  header_block[80..110].copy_from_slice(b"BITPIX  =                    8");
  header_block[160..190].copy_from_slice(b"NAXIS   =                    0");
  header_block[240..270].copy_from_slice(b"EXTEND  =                    T");
  header_block[320..323].copy_from_slice(b"END");
  writer.write_all(&header_block[..])?;
  Ok(())
}

/// # Params
/// - `dest` the
#[allow(dead_code)]
pub(super) fn write_uint_keyword_record(dest: &mut [u8], keyword: &[u8; 8], val: u64) {
  write_keyword_record(dest, keyword, &val.to_string())
}

/// # Params
/// - `dest` the
#[allow(dead_code)]
pub(super) fn write_str_keyword_record(dest: &mut [u8], keyword: &[u8; 8], val: &str) {
  write_keyword_record(dest, keyword, &format!("'{}'", val))
}

/// # Params
/// - `dest` destination, must contains 80 bytes
/// - `value_part` is string, must be already quote: `'str_value'`
pub(super) fn write_keyword_record(dest: &mut [u8], keyword: &[u8; 8], value_part: &str) {
  debug_assert_eq!(dest.len(), 80);
  dest[0..8].copy_from_slice(&keyword[..]);
  dest[8..10].copy_from_slice(VALUE_INDICATOR);
  let val_bytes = value_part.as_bytes();
  dest[10..10 + val_bytes.len()].copy_from_slice(val_bytes);
}

pub(super) fn write_uint_mandatory_keyword_record(dest: &mut [u8], keyword: &[u8; 8], val: u64) {
  debug_assert_eq!(dest.len(), 80);
  dest[0..8].copy_from_slice(&keyword[..]);
  dest[8..10].copy_from_slice(VALUE_INDICATOR);
  let val = val.to_string();
  let val_bytes = val.as_bytes();
  dest[30 - val_bytes.len()..30].copy_from_slice(val_bytes);
}

// READ PART

/// # Params
/// - `header_block`: re-usable header block used to avoid multiple allocations
pub(super) fn consume_primary_hdu<R: BufRead>(
  reader: &mut R,
  header_block: &mut [u8; 2880],
) -> Result<(), FitsError> {
  let mut chunks_of_80 = next_36_chunks_of_80_bytes(reader, header_block)?;
  // SIMPLE = 'T' => file compliant with the FITS standard
  check_keyword_and_val(chunks_of_80.next().unwrap(), b"SIMPLE ", b"T")?;
  chunks_of_80.next().unwrap(); // Do not check for BITPIX (we expect an empty header)
                                // NAXIS = 0 => we only support FITS files with no data in the primary HDU
  check_keyword_and_val(chunks_of_80.next().unwrap(), b"NAXIS ", b"0")?;
  // Ignore possible additional keywords
  while !contains_end(&mut chunks_of_80) {
    // Few chances to enter here (except if someone had a lot of things to say in the header)
    chunks_of_80 = next_36_chunks_of_80_bytes(reader, header_block)?;
  }
  Ok(())
}

pub(super) fn next_36_chunks_of_80_bytes<'a, R: BufRead>(
  reader: &'a mut R,
  header_block: &'a mut [u8; 2880],
) -> Result<ChunksExact<'a, u8>, FitsError> {
  reader
    .read_exact(header_block)
    .map_err(FitsError::Io)
    .map(|()| header_block.chunks_exact(80))
}

fn contains_end<'a, I: Iterator<Item = &'a [u8]>>(chunks_of_80: &'a mut I) -> bool {
  for kw_rc in chunks_of_80 {
    debug_assert_eq!(kw_rc.len(), 80);
    if &kw_rc[0..4] == b"END " {
      return true;
    }
  }
  false
}

pub(super) fn check_keyword_and_val(
  keyword_record: &[u8],
  expected_kw: &[u8],
  expected_val: &[u8],
) -> Result<(), FitsError> {
  check_expected_keyword(keyword_record, expected_kw)
    .and_then(|()| check_for_value_indicator(keyword_record))
    .and_then(|()| check_expected_value(keyword_record, expected_val))
}

pub(super) fn check_keyword_and_parse_uint_val<T>(
  keyword_record: &[u8],
  expected_kw: &[u8],
) -> Result<T, FitsError>
where
  T: Into<u64> + FromStr<Err = ParseIntError>,
{
  check_expected_keyword(keyword_record, expected_kw)
    .and_then(|()| check_for_value_indicator(keyword_record))
    .and_then(|()| parse_uint_val::<T>(keyword_record))
}

pub(super) fn check_keyword_and_get_str_val<'a>(
  keyword_record: &'a [u8],
  expected_kw: &[u8],
) -> Result<&'a str, FitsError> {
  check_expected_keyword(keyword_record, expected_kw)
    .and_then(|()| check_for_value_indicator(keyword_record))
    .and_then(|()| {
      // We go unsafe because FITS headers are not supposed to contain non-ASCII chars
      get_str_val_no_quote(keyword_record).map(|bytes| unsafe { str::from_utf8_unchecked(bytes) })
    })
}

pub(super) fn check_expected_keyword(
  keyword_record: &[u8],
  expected: &[u8],
) -> Result<(), FitsError> {
  debug_assert!(keyword_record.len() == 80); // length of a FITS keyword-record
  debug_assert!(expected.len() <= 8); // length of a FITS keyword
  if &keyword_record[..expected.len()] == expected {
    Ok(())
  } else {
    // We know what we put in it, so unsafe is ok here
    let expected = String::from(unsafe { str::from_utf8_unchecked(expected) }.trim_end());
    // Here, may contains binary data
    let actual = String::from_utf8_lossy(&keyword_record[..expected.len()])
      .trim_end()
      .to_string();
    // panic!("Ecpected: {}, Actual: {}", expected, String::from_utf8_lossy(&src[..]));
    Err(FitsError::UnexpectedKeyword(expected, actual))
  }
}

pub(super) fn check_for_value_indicator(keyword_record: &[u8]) -> Result<(), FitsError> {
  debug_assert!(keyword_record.len() == 80); // length of a FITS keyword-record
  if get_value_indicator(keyword_record) == VALUE_INDICATOR {
    Ok(())
  } else {
    let keyword_record = String::from_utf8_lossy(keyword_record)
      .trim_end()
      .to_string();
    Err(FitsError::ValueIndicatorNotFound(keyword_record))
  }
}

pub(super) fn get_keyword(keyword_record: &[u8]) -> &[u8] {
  &keyword_record[..8]
}
pub(super) fn get_value_indicator(keyword_record: &[u8]) -> &[u8] {
  &keyword_record[8..10]
}
pub(super) fn get_value(keyword_record: &[u8]) -> &[u8] {
  &keyword_record[10..]
}
pub(super) fn get_left_trimmed_value(keyword_record: &[u8]) -> &[u8] {
  get_value(keyword_record).trim_ascii_start()
}

pub(super) fn check_expected_value(
  keyword_record: &[u8],
  expected: &[u8],
) -> Result<(), FitsError> {
  debug_assert!(keyword_record.len() == 80); // length of a FITS keyword-record
  let src = get_value(keyword_record);
  let lt_src = src.trim_ascii_start();
  if lt_src.len() >= expected.len() && &lt_src[..expected.len()] == expected {
    Ok(())
  } else {
    let keyword = String::from_utf8_lossy(&src[0..8]).trim_end().to_string();
    // We know what we put in it, so unsae is ok here
    let expected = String::from(unsafe { str::from_utf8_unchecked(expected) });
    // Here, may contains binary data
    let actual = String::from_utf8_lossy(&lt_src[..expected.len()]).to_string();
    Err(FitsError::UnexpectedValue(keyword, expected, actual))
  }
}

/// We know that the expected value does not contains a simple quote.
/// A trim_end is applied so that the result does not contain leading or trailing spaces.
pub(super) fn get_str_val_no_quote(keyword_record: &[u8]) -> Result<&[u8], FitsError> {
  let mut it = get_left_trimmed_value(keyword_record).split_inclusive(|c| *c == b'\'');
  if let Some([b'\'']) = it.next() {
    if let Some([subslice @ .., b'\'']) = it.next() {
      return Ok(subslice.trim_ascii_end());
    }
  }
  let keyword_record = String::from_utf8_lossy(keyword_record)
    .trim_end()
    .to_string();
  Err(FitsError::StringValueNotFound(keyword_record))
}

pub(super) fn parse_uint_val<T>(keyword_record: &[u8]) -> Result<T, FitsError>
where
  T: Into<u64> + FromStr<Err = ParseIntError>,
{
  let src = get_left_trimmed_value(keyword_record);
  let to = index_of_last_digit(src);
  if to == 0 {
    let keyword_record = String::from_utf8_lossy(keyword_record)
      .trim_end()
      .to_string();
    Err(FitsError::UintValueNotFound(keyword_record))
  } else {
    // we go unsafe and unwrap because we already tested for regular digits
    let str_val = unsafe { str::from_utf8_unchecked(&src[..to]) };
    let res = str_val.parse::<T>().context(str_val.to_string())?;
    Ok(res)
  }
}

pub(super) fn index_of_last_digit(src: &[u8]) -> usize {
  for (i, c) in src.iter().enumerate() {
    if !c.is_ascii_digit() {
      return i;
    }
  }
  src.len()
}

#[cfg(test)]
mod tests {
  use crate::deser::fits::common::write_primary_hdu;

  #[test]
  fn test_write_primary_hdu() {
    let mut buf: Vec<u8> = Default::default();
    write_primary_hdu(&mut buf).unwrap();
    assert_eq!(buf.len(), 2880);
  }
}