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scanner: multibyte rune literals now support unicode, hex, and octal escape codes (#13140)
This commit is contained in:
jeffmikels
GitHub
parent
bb6c46e1ef
commit
7a2705d8ce
@ -16,6 +16,11 @@ indent_size = 2
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[*.md]
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trim_trailing_whitespace = false
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# lines that are too long will trigger an error in cmd/tools/vcheck-md.v
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# run v check-md [folder/file] to test markdown files
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# the longest normal line is specified with this constant:
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# `too_long_line_length_other = 100`
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max_line_length = 100
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[*.{txt,out}]
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insert_final_newline = false
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194
doc/docs.md
194
doc/docs.md
@ -476,16 +476,33 @@ d := b + x // d is of type `f64` - automatic promotion of `x`'s value
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### Strings
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```v
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```v nofmt
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name := 'Bob'
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println(name.len)
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println(name[0]) // indexing gives a byte B
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println(name[1..3]) // slicing gives a string 'ob'
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windows_newline := '\r\n' // escape special characters like in C
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assert name.len == 3 // will print 3
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assert name[0] == byte(66) // indexing gives a byte, byte(66) == `B`
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assert name[1..3] == 'ob' // slicing gives a string 'ob'
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// escape codes
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windows_newline := '\r\n' // escape special characters like in C
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assert windows_newline.len == 2
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// arbitrary bytes can be directly specified using `\x##` notation where `#` is
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// a hex digit aardvark_str := '\x61ardvark' assert aardvark_str == 'aardvark'
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assert '\xc0'[0] == byte(0xc0)
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// or using octal escape `\###` notation where `#` is an octal digit
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aardvark_str2 := '\141ardvark'
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assert aardvark_str2 == 'aardvark'
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// Unicode can be specified directly as `\u####` where # is a hex digit
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// and will be converted internally to its UTF-8 representation
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star_str := '\u2605' // ★
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assert star_str == '★'
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assert star_str == '\xe2\x98\x85' // UTF-8 can be specified this way too.
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```
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In V, a string is a read-only array of bytes. String data is encoded using UTF-8:
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In V, a string is a read-only array of bytes. All Unicode characters are encoded using UTF-8:
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```v
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s := 'hello 🌎' // emoji takes 4 bytes
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assert s.len == 10
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@ -503,11 +520,12 @@ String values are immutable. You cannot mutate elements:
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mut s := 'hello 🌎'
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s[0] = `H` // not allowed
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```
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> error: cannot assign to `s[i]` since V strings are immutable
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Note that indexing a string will produce a `byte`, not a `rune` nor another `string`.
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Indexes correspond to bytes in the string, not Unicode code points. If you want to
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convert the `byte` to a `string`, use the `ascii_str()` method:
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Note that indexing a string will produce a `byte`, not a `rune` nor another `string`. Indexes
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correspond to _bytes_ in the string, not Unicode code points. If you want to convert the `byte` to a
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`string`, use the `.ascii_str()` method on the `byte`:
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```v
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country := 'Netherlands'
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@ -515,20 +533,13 @@ println(country[0]) // Output: 78
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println(country[0].ascii_str()) // Output: N
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```
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Character literals have type `rune`. To denote them, use `
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Both single and double quotes can be used to denote strings. For consistency, `vfmt` converts double
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quotes to single quotes unless the string contains a single quote character.
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For raw strings, prepend `r`. Escape handling is not done for raw strings:
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```v
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rocket := `🚀`
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assert 'aloha!'[0] == `a`
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```
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Both single and double quotes can be used to denote strings. For consistency,
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`vfmt` converts double quotes to single quotes unless the string contains a single quote character.
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For raw strings, prepend `r`. Raw strings are not escaped:
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```v
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s := r'hello\nworld'
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s := r'hello\nworld' // the `\n` will be preserved as two characters
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println(s) // "hello\nworld"
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```
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@ -537,41 +548,79 @@ Strings can be easily converted to integers:
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```v
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s := '42'
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n := s.int() // 42
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// all int literals are supported
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assert '0xc3'.int() == 195
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assert '0o10'.int() == 8
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assert '0b1111_0000_1010'.int() == 3850
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assert '-0b1111_0000_1010'.int() == -3850
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```
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### Runes
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A `rune` represents a unicode character and is an alias for `u32`. Runes can be created like this:
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```v
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x := `🚀`
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```
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A string can be converted to runes by the `.runes()` method.
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```v
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hello := 'Hello World 👋'
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hello_runes := hello.runes() // [`H`, `e`, `l`, `l`, `o`, ` `, `W`, `o`, `r`, `l`, `d`, ` `, `👋`]
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```
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For more advanced `string` processing and conversions, refer to the
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[vlib/strconv](https://modules.vlang.io/strconv.html) module.
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### String interpolation
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Basic interpolation syntax is pretty simple - use `$` before a variable name.
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The variable will be converted to a string and embedded into the literal:
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Basic interpolation syntax is pretty simple - use `$` before a variable name. The variable will be
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converted to a string and embedded into the literal:
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```v
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name := 'Bob'
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println('Hello, $name!') // Hello, Bob!
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```
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It also works with fields: `'age = $user.age'`.
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If you need more complex expressions, use `${}`: `'can register = ${user.age > 13}'`.
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Format specifiers similar to those in C's `printf()` are also supported.
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`f`, `g`, `x`, etc. are optional and specify the output format.
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The compiler takes care of the storage size, so there is no `hd` or `llu`.
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It also works with fields: `'age = $user.age'`. If you need more complex expressions, use `${}`:
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`'can register = ${user.age > 13}'`.
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Format specifiers similar to those in C's `printf()` are also supported. `f`, `g`, `x`, `o`, `b`,
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etc. are optional and specify the output format. The compiler takes care of the storage size, so
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there is no `hd` or `llu`.
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To use a format specifier, follow this pattern:
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`${varname:[flags][width][.precision][type]}`
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- flags: may be zero or more of the following: `-` to left-align output within the field, `0` to use
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`0` as the padding character instead of the default `space` character. (Note: V does not currently
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support the use of `'` or `#` as format flags, and V supports but doesn't need `+` to right-align
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since that's the default.)
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- width: may be an integer value describing the minimum width of total field to output.
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- precision: an integer value preceeded by a `.` will guarantee that many digits after the decimal
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point, if the input variable is a float. Ignored if variable is an integer.
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- type: `f` and `F` specify the input is a float and should be rendered as such, `e` and `E` specify
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the input is a float and should be rendered as an exponent (partially broken), `g` and `G` specify
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the input is a float--the renderer will use floating point notation for small values and exponent
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notation for large values, `d` specifies the input is an integer and should be rendered in base-10
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digits, `x` and `X` require an integer and will render it as hexadecimal digits, `o` requires an
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integer and will render it as octal digits, `b` requires an integer and will render it as binary
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digits, `s` requires a string (almost never used).
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Note: when a numeric type can render alphabetic characters, such as hex strings or special values
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like `infinity`, the lowercase version of the type forces lowercase alphabetics and the uppercase
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version forces uppercase alphabetics.
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Also note: in most cases, it's best to leave the format type empty. Floats will be rendered by
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default as `g`, integers will be rendered by default as `d`, and `s` is almost always redundant.
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There are only three cases where specifying a type is recommended:
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- format strings are parsed at compile time, so specifing a type can help detect errors then
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- format strings default to using lowercase letters for hex digits and the `e` in exponents. Use a
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uppercase type to force the use of uppercase hex digits and an uppercase `E` in exponents.
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- format strings are the most convenient way to get hex, binary or octal strings from an integer.
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See
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[Format Placeholder Specification](https://en.wikipedia.org/wiki/Printf_format_string#Format_placeholder_specification)
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for more information.
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```v
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x := 123.4567
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println('x = ${x:4.2f}')
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println('[${x:10}]') // pad with spaces on the left => [ 123.457]
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println('[${int(x):-10}]') // pad with spaces on the right => [123 ]
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println('[${x:.2}]') // round to two decimal places => [123.46]
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println('[${x:10}]') // right-align with spaces on the left => [ 123.457]
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println('[${int(x):-10}]') // left-align with spaces on the right => [123 ]
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println('[${int(x):010}]') // pad with zeros on the left => [0000000123]
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println('[${int(x):b}]') // output as binary => [1111011]
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println('[${int(x):o}]') // output as octal => [173]
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println('[${int(x):X}]') // output as uppercase hex => [7B]
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```
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### String operators
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@ -585,13 +634,14 @@ s += 'world' // `+=` is used to append to a string
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println(s) // "hello world"
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```
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All operators in V must have values of the same type on both sides.
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You cannot concatenate an integer to a string:
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All operators in V must have values of the same type on both sides. You cannot concatenate an
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integer to a string:
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```v failcompile
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age := 10
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println('age = ' + age) // not allowed
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```
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> error: infix expr: cannot use `int` (right expression) as `string`
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We have to either convert `age` to a `string`:
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@ -608,6 +658,62 @@ age := 12
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println('age = $age')
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```
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### Runes
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A `rune` represents a single Unicode character and is an alias for `u32`. To denote them, use `
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(backticks) :
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```v
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rocket := `🚀`
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```
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A `rune` can be converted to a UTF-8 string by using the `.str()` method.
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```v
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rocket := `🚀`
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assert rocket.str() == '🚀'
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```
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A `rune` can be converted to UTF-8 bytes by using the `.bytes()` method.
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```v
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rocket := `🚀`
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assert rocket.bytes() == [byte(0xf0), 0x9f, 0x9a, 0x80]
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```
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Hex, Unicode, and Octal escape sequences also work in a `rune` literal:
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```v
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assert `\x61` == `a`
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assert `\141` == `a`
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assert `\u0061` == `a`
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// multibyte literals work too
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assert `\u2605` == `★`
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assert `\u2605`.bytes() == [byte(0xe2), 0x98, 0x85]
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assert `\xe2\x98\x85`.bytes() == [byte(0xe2), 0x98, 0x85]
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assert `\342\230\205`.bytes() == [byte(0xe2), 0x98, 0x85]
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```
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Note that `rune` literals use the same escape syntax as strings, but they can only hold one unicode
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character. Therefore, if your code does not specify a single Unicode character, you will receive an
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error at compile time.
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Also remember that strings are indexed as bytes, not runes, so beware:
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```v
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rocket_string := '🚀'
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assert rocket_string[0] != `🚀`
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assert 'aloha!'[0] == `a`
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```
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A string can be converted to runes by the `.runes()` method.
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```v
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hello := 'Hello World 👋'
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hello_runes := hello.runes() // [`H`, `e`, `l`, `l`, `o`, ` `, `W`, `o`, `r`, `l`, `d`, ` `, `👋`]
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```
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### Numbers
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```v
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0
examples/v_script.vsh
Normal file → Executable file
0
examples/v_script.vsh
Normal file → Executable file
@ -1307,6 +1307,28 @@ fn decode_h_escapes(s string, start int, escapes_pos []int) string {
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return ss.join('')
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}
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// handle single-byte inline octal escapes like '\###'
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fn decode_o_escapes(s string, start int, escapes_pos []int) string {
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if escapes_pos.len == 0 {
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return s
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}
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mut ss := []string{cap: escapes_pos.len}
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ss << s[..escapes_pos.first() - start] // everything before the first escape code position
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for i, pos in escapes_pos {
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idx := pos - start
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end_idx := idx + 4 // "\XXX".len == 4
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// notice this function doesn't do any decoding... it just replaces '\141' with the byte 0o141
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ss << [byte(strconv.parse_uint(s[idx + 1..end_idx], 8, 8) or { 0 })].bytestr()
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if i + 1 < escapes_pos.len {
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ss << s[end_idx..escapes_pos[i + 1] - start]
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} else {
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ss << s[end_idx..]
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}
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}
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return ss.join('')
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}
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// decode the flagged unicode escape sequences into their utf-8 bytes
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fn decode_u_escapes(s string, start int, escapes_pos []int) string {
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if escapes_pos.len == 0 {
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return s
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@ -1348,9 +1370,10 @@ fn trim_slash_line_break(s string) string {
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/// possibilities:
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/// single chars like `a`, `b` => 'a', 'b'
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/// escaped single chars like `\\`, `\``, `\n` => '\\', '`', '\n'
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/// escaped hex bytes like `\x01`, `\x61` => '\x01', 'a'
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/// escaped multibyte runes like `\xe29885` => (★)
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/// escaped single hex bytes like `\x01`, `\x61` => '\x01', 'a'
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/// escaped unicode literals like `\u2605`
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/// escaped utf8 runes in hex like `\xe2\x98\x85` => (★)
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/// escaped utf8 runes in octal like `\342\230\205` => (★)
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fn (mut s Scanner) ident_char() string {
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lspos := token.Position{
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line_nr: s.line_nr
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@ -1365,6 +1388,7 @@ fn (mut s Scanner) ident_char() string {
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// set flags for advanced escapes first
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escaped_hex := s.expect('\\x', start + 1)
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escaped_unicode := s.expect('\\u', start + 1)
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escaped_octal := !escaped_hex && !escaped_unicode && s.expect('\\', start + 1)
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// walk the string to get characters up to the next backtick
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for {
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@ -1390,65 +1414,40 @@ fn (mut s Scanner) ident_char() string {
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return c
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}
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if len != 1 {
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// the string inside the backticks is longer than one character
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// but we might only have one rune... attempt to decode escapes
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// if the content expresses an escape code, it will have an even number of characters
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// e.g. \x61 or \u2605
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if (c.len % 2 == 0) && (escaped_hex || escaped_unicode) {
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// e.g. (octal) \141 (hex) \x61 or (unicode) \u2605
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// we don't handle binary escape codes in rune literals
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orig := c
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if (c.len % 2 == 0) && (escaped_hex || escaped_unicode || escaped_octal) {
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if escaped_unicode {
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// there can only be one, so attempt to decode it now
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c = decode_u_escapes(c, 0, [0])
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} else {
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// we have to handle hex ourselves
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ascii_0 := byte(0x30)
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ascii_a := byte(0x61)
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mut accumulated := []byte{}
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val := c[2..c.len].to_lower() // 0A -> 0a
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mut offset := 0
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// take two characters at a time, parse as hex and add to bytes
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for {
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if offset >= val.len - 1 {
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break
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// find escape sequence start positions
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mut escapes_pos := []int{}
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for i, v in c {
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if v == `\\` {
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escapes_pos << i
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}
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mut byteval := byte(0)
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big := val[offset]
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little := val[offset + 1]
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if !big.is_hex_digit() {
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accumulated.clear()
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break
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}
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if !little.is_hex_digit() {
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accumulated.clear()
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break
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}
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if big.is_digit() {
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byteval |= (big - ascii_0) << 4
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} else {
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byteval |= (big - ascii_a + 10) << 4
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}
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if little.is_digit() {
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byteval |= (little - ascii_0)
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} else {
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byteval |= (little - ascii_a + 10)
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}
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accumulated << byteval
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offset += 2
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}
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if accumulated.len > 0 {
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c = accumulated.bytestr()
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if escaped_hex {
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c = decode_h_escapes(c, 0, escapes_pos)
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} else {
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c = decode_o_escapes(c, 0, escapes_pos)
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}
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}
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}
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// the string inside the backticks is longer than one character
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// but we might only have one rune, say in the case
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u := c.runes()
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if u.len != 1 {
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if escaped_hex || escaped_unicode {
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s.error('invalid character literal (escape sequence did not refer to a singular rune)')
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s.error('invalid character literal `$orig` => `$c` ($u) (escape sequence did not refer to a singular rune)')
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} else {
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s.add_error_detail_with_pos('use quotes for strings, backticks for characters',
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lspos)
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s.error('invalid character literal (more than one character)')
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s.error('invalid character literal `$orig` => `$c` ($u) (more than one character)')
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}
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}
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}
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@ -150,13 +150,19 @@ fn test_ref_ref_array_ref_ref_foo() {
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assert result[6] == .name
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}
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fn test_escape_string() {
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// these assertions aren't helpful...
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// they test the vlib built-in to the compiler,
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// but we want to test this module before compilation
|
||||
assert '\x61' == 'a'
|
||||
assert '\x62' == 'b'
|
||||
// assert `\x61` == `a` // will work after pull request goes through
|
||||
fn test_escape_rune() {
|
||||
// these lines work if the v compiler is working
|
||||
// will not work until v compiler on github is updated
|
||||
// assert `\x61` == `a`
|
||||
// assert `\u0061` == `a`
|
||||
|
||||
// will not work until PR is accepted
|
||||
// assert `\141` == `a`
|
||||
// assert `\xe2\x98\x85` == `★`
|
||||
// assert `\342\230\205` == `★`
|
||||
|
||||
// the following lines test the scanner module
|
||||
// even before it is compiled into the v executable
|
||||
|
||||
// SINGLE CHAR ESCAPES
|
||||
// SINGLE CHAR APOSTROPHE
|
||||
@ -187,14 +193,30 @@ fn test_escape_string() {
|
||||
// SINGLE CHAR INCORRECT ESCAPE
|
||||
// result = scan_tokens(r'`\x61\x61`') // should always result in an error
|
||||
|
||||
// SINGLE CHAR MULTI-BYTE UTF-8
|
||||
// Compilation blocked by vlib/v/checker/check_types.v, but works in the repl
|
||||
result = scan_tokens(r'`\xe29885`')
|
||||
// SINGLE CHAR MULTI-BYTE UTF-8 (hex)
|
||||
result = scan_tokens(r'`\xe2\x98\x85`')
|
||||
assert result[0].lit == r'★'
|
||||
|
||||
// SINGLE CHAR MULTI-BYTE UTF-8 (octal)
|
||||
result = scan_tokens(r'`\342\230\205`')
|
||||
assert result[0].lit == r'★'
|
||||
}
|
||||
|
||||
fn test_escape_string() {
|
||||
// these lines work if the v compiler is working
|
||||
assert '\x61' == 'a'
|
||||
assert '\x62' == 'b'
|
||||
assert '\u0061' == 'a'
|
||||
assert '\141' == 'a'
|
||||
assert '\xe2\x98\x85' == '★'
|
||||
assert '\342\230\205' == '★'
|
||||
|
||||
// the following lines test the scanner module
|
||||
// even before it is compiled into the v executable
|
||||
|
||||
// STRING ESCAPES =================
|
||||
// STRING APOSTROPHE
|
||||
result = scan_tokens(r"'\''")
|
||||
mut result := scan_tokens(r"'\''")
|
||||
assert result[0].kind == .string
|
||||
assert result[0].lit == r"\'"
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user