devela 0.27.0

A development layer of coherence.
Documentation 
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// devela::text::parse::tests

use crate::{TextParseErrorKind, TextScanner};

/* construction, views, and cursor state */

#[test]
fn construction_views_and_state() {
    let mut s = TextScanner::new("abc");
    assert_eq!(s.pos().as_usize(), 0);
    assert!(!s.is_eof());
    assert_eq!(s.rest(), b"abc");

    let start = s.mark();
    assert_eq!(s.next_byte(), Some(b'a'));
    assert_eq!(s.next_byte(), Some(b'b'));
    let range = s.range_from(start);

    assert_eq!(s.slice(range), b"ab");
    assert_eq!(s.slice_str(range), Some("ab"));
    assert_eq!(s.rest(), b"c");

    assert_eq!(s.next_byte(), Some(b'c'));
    assert_eq!(s.next_byte(), None);
    assert!(s.is_eof());
    assert_eq!(s.rest(), b"");
}

/* byte inspection and exact consumption */

#[test]
fn byte_ops() {
    let mut s = TextScanner::new("abc\r\ndef");

    assert_eq!(s.peek_byte(), Some(b'a'));
    assert_eq!(s.eat_byte(b'x'), false);
    assert_eq!(s.pos().as_usize(), 0);

    assert_eq!(s.eat_byte(b'a'), true);
    assert_eq!(s.pos().as_usize(), 1);

    assert_eq!(s.eat_bytes(b"bc"), true);
    assert_eq!(s.pos().as_usize(), 3);

    assert_eq!(s.eat_eol(), true);
    assert_eq!(s.pos().as_usize(), 5);

    assert_eq!(s.expect_bytes(b"def"), Ok(()));
    assert!(s.is_eof());
}

#[test]
fn expect_ops_do_not_advance_on_failure() {
    let mut s = TextScanner::new("abc");

    assert!(s.expect_byte(b'x').is_err());
    assert_eq!(s.pos().as_usize(), 0);

    assert!(s.expect_bytes(b"ax").is_err());
    assert_eq!(s.pos().as_usize(), 0);

    assert!(s.expect_bytes(b"abcd").is_err());
    assert_eq!(s.pos().as_usize(), 0);
}

/* ascii scanning and range-taking */

#[test]
fn ascii_scanners() {
    let mut s = TextScanner::new(" \t\r\nfoo_12 123bar");
    s.skip_ascii_ws();
    assert_eq!(s.pos().as_usize(), 4);

    let ident = s.take_ascii_ident().unwrap();
    assert_eq!(s.slice_str(ident), Some("foo_12"));
    assert_eq!(s.peek_byte(), Some(b' '));

    s.skip_ascii_ws();
    assert_eq!(s.expect_ascii_u64(), Ok(123));
    assert_eq!(s.rest(), b"bar");
}

#[test]
fn ascii_u64_edge_cases() {
    let mut s = TextScanner::new("abc");
    assert_eq!(s.take_ascii_u64(), Ok(None));
    assert!(s.expect_ascii_u64().is_err());
    assert_eq!(s.pos().as_usize(), 0);

    let mut s = TextScanner::new("18446744073709551615!");
    assert_eq!(s.take_ascii_u64(), Ok(Some(u64::MAX)));
    assert_eq!(s.peek_byte(), Some(b'!'));

    let mut s = TextScanner::new("18446744073709551616!");
    assert!(s.take_ascii_u64().is_err());
    assert_eq!(s.pos().as_usize(), 19); // stops before the offending digit
    assert_eq!(s.peek_byte(), Some(b'6'));
}

#[test]
fn take_until_variants() {
    let mut s = TextScanner::new("abc:def,ghi\r\nrest");

    let r = s.take_until_byte(b':');
    assert_eq!(s.slice_str(r), Some("abc"));
    assert_eq!(s.peek_byte(), Some(b':'));
    let _ = s.eat_byte(b':');

    let r = s.take_until_any2(b',', b';');
    assert_eq!(s.slice_str(r), Some("def"));
    assert_eq!(s.peek_byte(), Some(b','));
    let _ = s.eat_byte(b',');

    let r = s.take_until_any3(b'X', b'Y', b'\r');
    assert_eq!(s.slice_str(r), Some("ghi"));
    assert_eq!(s.peek_byte(), Some(b'\r'));

    let r = s.take_until_eol();
    assert_eq!(s.slice_str(r), Some(""));
    assert_eq!(s.peek_byte(), Some(b'\r'));

    assert_eq!(s.eat_eol(), true);
    assert_eq!(s.rest(), b"rest");
}

#[test]
fn take_until_bytes_regression_nonzero_cursor() {
    let mut s = TextScanner::new("xx--yy--zz");

    assert_eq!(s.expect_bytes(b"xx"), Ok(()));
    assert_eq!(s.pos().as_usize(), 2);

    let r = s.take_until_bytes(b"--");
    assert_eq!(s.slice_str(r), Some(""));
    assert_eq!(s.pos().as_usize(), 2);

    assert_eq!(s.eat_bytes(b"--"), true);
    assert_eq!(s.pos().as_usize(), 4);

    let r = s.take_until_bytes(b"--");
    assert_eq!(s.slice_str(r), Some("yy"));
    assert_eq!(s.pos().as_usize(), 6);

    assert_eq!(s.eat_bytes(b"--"), true);
    assert_eq!(s.pos().as_usize(), 8);

    let r = s.take_until_bytes(b"??");
    assert_eq!(s.slice_str(r), Some("zz"));
    assert_eq!(s.pos().as_usize(), 10);
    assert!(s.is_eof());
}

/* quoted strings */

#[test]
fn quoted_scanning_and_decoding() {
    let mut s = TextScanner::new(r#""a\n\"b" 'x\y'"#);

    let basic = s.take_quoted_basic().unwrap().unwrap();
    assert_eq!(s.slice(basic), br#"a\n\"b"#);

    let mut out = [0u8; 16];
    let len = s.decode_quoted_basic_into(basic, &mut out).unwrap();
    assert_eq!(&out[..len], b"a\n\"b");

    let text = s.decode_quoted_basic_str_into(basic, &mut out).unwrap();
    assert_eq!(text, "a\n\"b");

    s.skip_ascii_ws();

    let lit = s.take_quoted_literal().unwrap().unwrap();
    assert_eq!(s.slice(lit), br#"x\y"#);
}

#[test]
fn quoted_decode_errors() {
    // trailing backslash
    let mut s = TextScanner::from_bytes(b"a\\");
    let start = s.mark();
    let _ = s.next_byte();
    let _ = s.next_byte();
    let range = s.range_from(start);

    let mut out = [0u8; 8];
    assert!(s.decode_quoted_basic_into(range, &mut out).is_err());

    // invalid escape
    let mut s = TextScanner::from_bytes(b"\\x");
    let start = s.mark();
    let _ = s.next_byte();
    let _ = s.next_byte();
    let range = s.range_from(start);

    let mut out = [0u8; 8];
    assert!(s.decode_quoted_basic_into(range, &mut out).is_err());
}

#[test]
fn quoted_decode_invalid_utf8() {
    let mut s = TextScanner::from_bytes(&[0xFF]);
    let start = s.mark();
    let _ = s.next_byte();
    let range = s.range_from(start);

    let mut out = [0u8; 8];
    let err = s.decode_quoted_basic_str_into(range, &mut out).unwrap_err();

    assert_eq!(err.at.index.as_usize(), 0);
    match err.kind {
        TextParseErrorKind::InvalidUtf8(e) => {
            assert_eq!(e.valid_up_to, 0);
            assert_eq!(e.error_len, Some(1));
        }
        other => panic!("unexpected error kind: {other:?}"),
    }
}

#[test]
fn quoted_decode_invalid_escape() {
    let mut s = TextScanner::from_bytes(b"\\x");
    let start = s.mark();
    let _ = s.next_byte();
    let _ = s.next_byte();
    let range = s.range_from(start);

    let mut out = [0u8; 8];
    let err = s.decode_quoted_basic_into(range, &mut out).unwrap_err();

    assert_eq!(err.at.index.as_usize(), 1);
    assert!(matches!(err.kind, TextParseErrorKind::InvalidEscape));
}

#[test]
fn quoted_decode_trailing_backslash() {
    let mut s = TextScanner::from_bytes(b"a\\");
    let start = s.mark();
    let _ = s.next_byte();
    let _ = s.next_byte();
    let range = s.range_from(start);

    let mut out = [0u8; 8];
    let err = s.decode_quoted_basic_into(range, &mut out).unwrap_err();

    assert_eq!(err.at.index.as_usize(), 2);
    assert!(matches!(err.kind, TextParseErrorKind::UnterminatedQuote));
}

#[test]
fn quoted_decode_buffer_too_small() {
    let mut s = TextScanner::new(r#""abcd""#);
    let range = s.take_quoted_basic().unwrap().unwrap();

    let mut out = [0u8; 2];
    assert!(s.decode_quoted_basic_into(range, &mut out).is_err());
}

/* predicate-driven adapters */

#[test]
fn predicate_adapters() {
    let mut s = TextScanner::new("123abc456");

    let n = s.skip_while(|b| b.is_ascii_digit());
    assert_eq!(n, 3);
    assert_eq!(s.rest(), b"abc456");

    let r = s.take_while(|b| b.is_ascii_alphabetic());
    assert_eq!(s.slice_str(r), Some("abc"));
    assert_eq!(s.rest(), b"456");

    let r = s.take_while(|b| b.is_ascii_digit());
    assert_eq!(s.slice_str(r), Some("456"));
    assert!(s.is_eof());
}