String [Src]

A String is an ordered collection of characters.

Strings don't specify an encoding.

Example usage of some common String methods:

actor Main
  new create(env: Env) =>
    try
      // construct a new string
      let str = "Hello"

      // make an uppercased version
      let str_upper = str.upper()
      // make a reversed version
      let str_reversed = str.reverse()

      // add " world" to the end of our original string
      let str_new = str.add(" world")

      // count occurrences of letter "l"
      let count = str_new.count("l")

      // find first occurrence of letter "w"
      let first_w = str_new.find("w")
      // find first occurrence of letter "d"
      let first_d = str_new.find("d")

      // get substring capturing "world"
      let substr = str_new.substring(first_w, first_d+1)
      // clone substring
      let substr_clone = substr.clone()

      // print our substr
      env.out.print(consume substr)
  end

class val String is
  Seq[U8 val] ref,
  Comparable[String box] ref,
  Stringable box

Implements

• Seq[U8 val] ref
• Comparable[String box] ref
• Stringable box

---

Constructors

create [Src]

An empty string. Enough space for len bytes is reserved.

new ref create(
  len: USize val = seq)
: String ref^

Parameters

• len: USize val = seq

Returns

• String ref^

---

from_array [Src]

Create a string from an array, reusing the underlying data pointer.

new val from_array(
  data: Array[U8 val] val)
: String val^

Parameters

• data: Array[U8 val] val

Returns

• String val^

---

from_iso_array [Src]

Create a string from an array, reusing the underlying data pointer

new iso from_iso_array(
  data: Array[U8 val] iso)
: String iso^

Parameters

• data: Array[U8 val] iso

Returns

• String iso^

---

from_cpointer [Src]

Return a string from binary pointer data without making a copy. This must be done only with C-FFI functions that return pony_alloc'd character arrays. If a null pointer is given then an empty string is returned.

new ref from_cpointer(
  str: Pointer[U8 val] ref,
  len: USize val,
  alloc: USize val = seq)
: String ref^

Parameters

• str: Pointer[U8 val] ref
• len: USize val
• alloc: USize val = seq

Returns

• String ref^

---

from_cstring [Src]

Return a string from a pointer to a null-terminated cstring without making a copy. The data is not copied. This must be done only with C-FFI functions that return pony_alloc'd character arrays. The pointer is scanned for the first null byte, which will be interpreted as the null terminator. Note that the scan is unbounded; the pointed to data must be null-terminated within the allocated array to preserve memory safety. If a null pointer is given then an empty string is returned.

new ref from_cstring(
  str: Pointer[U8 val] ref)
: String ref^

Parameters

• str: Pointer[U8 val] ref

Returns

• String ref^

---

copy_cpointer [Src]

Create a string by copying a fixed number of bytes from a pointer.

new ref copy_cpointer(
  str: Pointer[U8 val] box,
  len: USize val)
: String ref^

Parameters

• str: Pointer[U8 val] box
• len: USize val

Returns

• String ref^

---

copy_cstring [Src]

Create a string by copying a null-terminated C string. Note that the scan is unbounded; the pointed to data must be null-terminated within the allocated array to preserve memory safety. If a null pointer is given then an empty string is returned.

new ref copy_cstring(
  str: Pointer[U8 val] box)
: String ref^

Parameters

• str: Pointer[U8 val] box

Returns

• String ref^

---

from_utf32 [Src]

Create a UTF-8 string from a single UTF-32 code point.

new ref from_utf32(
  value: U32 val)
: String ref^

Parameters

• value: U32 val

Returns

• String ref^

---

Public Functions

push_utf32 [Src]

Push a UTF-32 code point.

fun ref push_utf32(
  value: U32 val)
: None val

Parameters

• value: U32 val

Returns

• None val

---

cpointer [Src]

Returns a C compatible pointer to the underlying string allocation.

fun box cpointer(
  offset: USize val = seq)
: Pointer[U8 val] tag

Parameters

• offset: USize val = seq

Returns

• Pointer[U8 val] tag

---

cstring [Src]

Returns a C compatible pointer to a null-terminated version of the string, safe to pass to an FFI function that doesn't accept a size argument, expecting a null-terminator. If the underlying string is already null terminated, this is returned; otherwise the string is copied into a new, null-terminated allocation.

fun box cstring()
: Pointer[U8 val] tag

Returns

• Pointer[U8 val] tag

---

array [Src]

Returns an Array[U8] that that reuses the underlying data pointer.

fun val array()
: Array[U8 val] val

Returns

• Array[U8 val] val

---

size [Src]

Returns the length of the string data in bytes.

fun box size()
: USize val

Returns

• USize val

---

codepoints [Src]

Returns the number of unicode code points in the string between the two offsets. Index range [from .. to) is half-open.

fun box codepoints(
  from: ISize val = seq,
  to: ISize val = seq)
: USize val

Parameters

• from: ISize val = seq
• to: ISize val = seq

Returns

• USize val

---

space [Src]

Returns the space available for data, not including the null terminator.

fun box space()
: USize val

Returns

• USize val

---

reserve [Src]

Reserve space for len bytes. An additional byte will be reserved for the null terminator.

fun ref reserve(
  len: USize val)
: None val

Parameters

• len: USize val

Returns

• None val

---

compact [Src]

Try to remove unused space, making it available for garbage collection. The request may be ignored. The string is returned to allow call chaining.

fun ref compact()
: None val

Returns

• None val

---

recalc [Src]

Recalculates the string length. This is only needed if the string is changed via an FFI call. If a null terminator byte is not found within the allocated length, the size will not be changed.

fun ref recalc()
: None val

Returns

• None val

---

truncate [Src]

Truncates the string at the minimum of len and space. Ensures there is a null terminator. Does not check for null terminators inside the string.

Note that memory is not freed by this operation.

fun ref truncate(
  len: USize val)
: None val

Parameters

• len: USize val

Returns

• None val

---

trim_in_place [Src]

Trim the string to a portion of itself, covering from until to. Unlike slice, the operation does not allocate a new string nor copy elements.

fun ref trim_in_place(
  from: USize val = seq,
  to: USize val = seq)
: None val

Parameters

• from: USize val = seq
• to: USize val = seq

Returns

• None val

---

trim [Src]

Return a shared portion of this string, covering from until to. Both the original and the new string are immutable, as they share memory. The operation does not allocate a new string pointer nor copy elements.

fun val trim(
  from: USize val = seq,
  to: USize val = seq)
: String val

Parameters

• from: USize val = seq
• to: USize val = seq

Returns

• String val

---

is_null_terminated [Src]

Return true if the string is null-terminated and safe to pass to an FFI function that doesn't accept a size argument, expecting a null-terminator. This method checks that there is a null byte just after the final position of populated bytes in the string, but does not check for other null bytes which may be present earlier in the content of the string. If you need a null-terminated copy of this string, use the clone method.

fun box is_null_terminated()
: Bool val

Returns

• Bool val

---

utf32 [Src]

Return a UTF32 representation of the character at the given offset and the number of bytes needed to encode that character. If the offset does not point to the beginning of a valid UTF8 encoding, return 0xFFFD (the unicode replacement character) and a length of one. Raise an error if the offset is out of bounds.

fun box utf32(
  offset: ISize val)
: (U32 val , U8 val) ?

Parameters

• offset: ISize val

Returns

• (U32 val , U8 val) ?

---

apply [Src]

Returns the i-th byte. Raise an error if the index is out of bounds.

fun box apply(
  i: USize val)
: U8 val ?

Parameters

• i: USize val

Returns

• U8 val ?

---

update [Src]

Change the i-th byte. Raise an error if the index is out of bounds.

fun ref update(
  i: USize val,
  value: U8 val)
: U8 val ?

Parameters

• i: USize val
• value: U8 val

Returns

• U8 val ?

---

at_offset [Src]

Returns the byte at the given offset. Raise an error if the offset is out of bounds.

fun box at_offset(
  offset: ISize val)
: U8 val ?

Parameters

• offset: ISize val

Returns

• U8 val ?

---

update_offset [Src]

Changes a byte in the string, returning the previous byte at that offset. Raise an error if the offset is out of bounds.

fun ref update_offset(
  offset: ISize val,
  value: U8 val)
: U8 val ?

Parameters

• offset: ISize val
• value: U8 val

Returns

• U8 val ?

---

clone [Src]

Returns a copy of the string. The resulting string is null-terminated even if the original is not.

fun box clone()
: String iso^

Returns

• String iso^

---

find [Src]

Return the index of the n-th instance of s in the string starting from the beginning. Raise an error if there is no n-th occurrence of s or s is empty.

fun box find(
  s: String box,
  offset: ISize val = seq,
  nth: USize val = seq)
: ISize val ?

Parameters

• s: String box
• offset: ISize val = seq
• nth: USize val = seq

Returns

• ISize val ?

---

rfind [Src]

Return the index of n-th instance of s in the string starting from the end. The offset represents the highest index to included in the search. Raise an error if there is no n-th occurrence of s or s is empty.

fun box rfind(
  s: String box,
  offset: ISize val = seq,
  nth: USize val = seq)
: ISize val ?

Parameters

• s: String box
• offset: ISize val = seq
• nth: USize val = seq

Returns

• ISize val ?

---

contains [Src]

Returns true if contains s as a substring, false otherwise.

fun box contains(
  s: String box,
  offset: ISize val = seq,
  nth: USize val = seq)
: Bool val

Parameters

• s: String box
• offset: ISize val = seq
• nth: USize val = seq

Returns

• Bool val

---

count [Src]

Counts the non-overlapping occurrences of s in the string.

fun box count(
  s: String box,
  offset: ISize val = seq)
: USize val

Parameters

• s: String box
• offset: ISize val = seq

Returns

• USize val

---

at [Src]

Returns true if the substring s is present at the given offset.

fun box at(
  s: String box,
  offset: ISize val = seq)
: Bool val

Parameters

• s: String box
• offset: ISize val = seq

Returns

• Bool val

---

delete [Src]

Delete len bytes at the supplied offset, compacting the string in place.

fun ref delete(
  offset: ISize val,
  len: USize val = seq)
: None val

Parameters

• offset: ISize val
• len: USize val = seq

Returns

• None val

---

substring [Src]

Returns a substring. Index range [from .. to) is half-open. Returns an empty string if nothing is in the range.

Note that this operation allocates a new string to be returned. For similar operations that don't allocate a new string, see trim and trim_in_place.

fun box substring(
  from: ISize val,
  to: ISize val = seq)
: String iso^

Parameters

• from: ISize val
• to: ISize val = seq

Returns

• String iso^

---

lower [Src]

Returns a lower case version of the string.

fun box lower()
: String iso^

Returns

• String iso^

---

lower_in_place [Src]

Transforms the string to lower case. Currently only knows ASCII case.

fun ref lower_in_place()
: None val

Returns

• None val

---

upper [Src]

Returns an upper case version of the string. Currently only knows ASCII case.

fun box upper()
: String iso^

Returns

• String iso^

---

upper_in_place [Src]

Transforms the string to upper case.

fun ref upper_in_place()
: None val

Returns

• None val

---

reverse [Src]

Returns a reversed version of the string.

fun box reverse()
: String iso^

Returns

• String iso^

---

reverse_in_place [Src]

Reverses the byte order in the string. This needs to be changed to handle UTF-8 correctly.

fun ref reverse_in_place()
: None val

Returns

• None val

---

push [Src]

Add a byte to the end of the string.

fun ref push(
  value: U8 val)
: None val

Parameters

• value: U8 val

Returns

• None val

---

pop [Src]

Remove a byte from the end of the string.

fun ref pop()
: U8 val ?

Returns

• U8 val ?

---

unshift [Src]

Adds a byte to the beginning of the string.

fun ref unshift(
  value: U8 val)
: None val

Parameters

• value: U8 val

Returns

• None val

---

shift [Src]

Removes a byte from the beginning of the string.

fun ref shift()
: U8 val ?

Returns

• U8 val ?

---

append [Src]

Append the elements from a sequence, starting from the given offset.

fun ref append(
  seq: ReadSeq[U8 val] box,
  offset: USize val = seq,
  len: USize val = seq)
: None val

Parameters

• seq: ReadSeq[U8 val] box
• offset: USize val = seq
• len: USize val = seq

Returns

• None val

---

concat [Src]

Add len iterated bytes to the end of the string, starting from the given offset.

fun ref concat(
  iter: Iterator[U8 val] ref,
  offset: USize val = seq,
  len: USize val = seq)
: None val

Parameters

• iter: Iterator[U8 val] ref
• offset: USize val = seq
• len: USize val = seq

Returns

• None val

---

clear [Src]

Truncate the string to zero length.

fun ref clear()
: None val

Returns

• None val

---

insert [Src]

Returns a version of the string with the given string inserted at the given offset.

fun box insert(
  offset: ISize val,
  that: String val)
: String iso^

Parameters

• offset: ISize val
• that: String val

Returns

• String iso^

---

insert_in_place [Src]

Inserts the given string at the given offset. Appends the string if the offset is out of bounds.

fun ref insert_in_place(
  offset: ISize val,
  that: String box)
: None val

Parameters

• offset: ISize val
• that: String box

Returns

• None val

---

insert_byte [Src]

Inserts a byte at the given offset. Appends if the offset is out of bounds.

fun ref insert_byte(
  offset: ISize val,
  value: U8 val)
: None val

Parameters

• offset: ISize val
• value: U8 val

Returns

• None val

---

cut [Src]

Returns a version of the string with the given range deleted. Index range [from .. to) is half-open.

fun box cut(
  from: ISize val,
  to: ISize val = seq)
: String iso^

Parameters

• from: ISize val
• to: ISize val = seq

Returns

• String iso^

---

cut_in_place [Src]

Cuts the given range out of the string. Index range [from .. to) is half-open.

fun ref cut_in_place(
  from: ISize val,
  to: ISize val = seq)
: None val

Parameters

• from: ISize val
• to: ISize val = seq

Returns

• None val

---

remove [Src]

Remove all instances of s from the string. Returns the count of removed instances.

fun ref remove(
  s: String box)
: USize val

Parameters

• s: String box

Returns

• USize val

---

replace [Src]

Replace up to n occurrences of from in this with to. If n is 0, all occurrences will be replaced. Returns the count of replaced occurrences.

fun ref replace(
  from: String box,
  to: String box,
  n: USize val = seq)
: USize val

Parameters

• from: String box
• to: String box
• n: USize val = seq

Returns

• USize val

---

split_by [Src]

Split the string into an array of strings that are delimited by delim in the original string. If n > 0, then the split count is limited to n.

Adjacent delimiters result in a zero length entry in the array. For example, "1,,2".split(",") => ["1", "", "2"].

An empty delimiter results in an array that contains a single element equal to the whole string.

fun box split_by(
  delim: String val,
  n: USize val = seq)
: Array[String val] iso^

Parameters

• delim: String val
• n: USize val = seq

Returns

• Array[String val] iso^

---

split [Src]

Split the string into an array of strings. Any character in the delimiter string is accepted as a delimiter. If n > 0, then the split count is limited to n.

Adjacent delimiters result in a zero length entry in the array. For example, "1,,2".split(",") => ["1", "", "2"].

fun box split(
  delim: String val = seq,
  n: USize val = seq)
: Array[String val] iso^

Parameters

• delim: String val = seq
• n: USize val = seq

Returns

• Array[String val] iso^

---

strip [Src]

Remove all leading and trailing characters from the string that are in s.

fun ref strip(
  s: String box = seq)
: None val

Parameters

• s: String box = seq

Returns

• None val

---

rstrip [Src]

Remove all trailing characters within the string that are in s. By default, trailing whitespace is removed.

fun ref rstrip(
  s: String box = seq)
: None val

Parameters

• s: String box = seq

Returns

• None val

---

lstrip [Src]

Remove all leading characters within the string that are in s. By default, leading whitespace is removed.

fun ref lstrip(
  s: String box = seq)
: None val

Parameters

• s: String box = seq

Returns

• None val

---

add [Src]

Return a string that is a concatenation of this and that.

fun box add(
  that: String box)
: String val

Parameters

• that: String box

Returns

• String val

---

join [Src]

Return a string that is a concatenation of the strings in data, using this as a separator.

fun box join(
  data: Iterator[Stringable box] ref)
: String iso^

Parameters

• data: Iterator[Stringable box] ref

Returns

• String iso^

---

compare [Src]

Lexically compare two strings.

fun box compare(
  that: String box)
: (Less val | Equal val | Greater val)

Parameters

• that: String box

Returns

• (Less val | Equal val | Greater val)

---

compare_sub [Src]

Lexically compare at most n bytes of the substring of this starting at offset with the substring of that starting at that_offset. The comparison is case sensitive unless ignore_case is true.

If the substring of this is a proper prefix of the substring of that, then this is Less than that. Likewise, if that is a proper prefix of this, then this is Greater than that.

Both offset and that_offset can be negative, in which case the offsets are computed from the end of the string.

If n + offset is greater than the length of this, or n + that_offset is greater than the length of that, then the number of positions compared will be reduced to the length of the longest substring.

Needs to be made UTF-8 safe.

fun box compare_sub(
  that: String box,
  n: USize val,
  offset: ISize val = seq,
  that_offset: ISize val = seq,
  ignore_case: Bool val = seq)
: (Less val | Equal val | Greater val)

Parameters

• that: String box
• n: USize val
• offset: ISize val = seq
• that_offset: ISize val = seq
• ignore_case: Bool val = seq

Returns

• (Less val | Equal val | Greater val)

---

eq [Src]

Returns true if the two strings have the same contents.

fun box eq(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---

lt [Src]

Returns true if this is lexically less than that. Needs to be made UTF-8 safe.

fun box lt(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---

le [Src]

Returns true if this is lexically less than or equal to that. Needs to be made UTF-8 safe.

fun box le(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---

offset_to_index [Src]

fun box offset_to_index(
  i: ISize val)
: USize val

Parameters

• i: ISize val

Returns

• USize val

---

bool [Src]

fun box bool()
: Bool val ?

Returns

• Bool val ?

---

i8 [Src]

fun box i8(
  base: U8 val = seq)
: I8 val ?

Parameters

• base: U8 val = seq

Returns

• I8 val ?

---

i16 [Src]

fun box i16(
  base: U8 val = seq)
: I16 val ?

Parameters

• base: U8 val = seq

Returns

• I16 val ?

---

i32 [Src]

fun box i32(
  base: U8 val = seq)
: I32 val ?

Parameters

• base: U8 val = seq

Returns

• I32 val ?

---

i64 [Src]

fun box i64(
  base: U8 val = seq)
: I64 val ?

Parameters

• base: U8 val = seq

Returns

• I64 val ?

---

i128 [Src]

fun box i128(
  base: U8 val = seq)
: I128 val ?

Parameters

• base: U8 val = seq

Returns

• I128 val ?

---

ilong [Src]

fun box ilong(
  base: U8 val = seq)
: ILong val ?

Parameters

• base: U8 val = seq

Returns

• ILong val ?

---

isize [Src]

fun box isize(
  base: U8 val = seq)
: ISize val ?

Parameters

• base: U8 val = seq

Returns

• ISize val ?

---

u8 [Src]

fun box u8(
  base: U8 val = seq)
: U8 val ?

Parameters

• base: U8 val = seq

Returns

• U8 val ?

---

u16 [Src]

fun box u16(
  base: U8 val = seq)
: U16 val ?

Parameters

• base: U8 val = seq

Returns

• U16 val ?

---

u32 [Src]

fun box u32(
  base: U8 val = seq)
: U32 val ?

Parameters

• base: U8 val = seq

Returns

• U32 val ?

---

u64 [Src]

fun box u64(
  base: U8 val = seq)
: U64 val ?

Parameters

• base: U8 val = seq

Returns

• U64 val ?

---

u128 [Src]

fun box u128(
  base: U8 val = seq)
: U128 val ?

Parameters

• base: U8 val = seq

Returns

• U128 val ?

---

ulong [Src]

fun box ulong(
  base: U8 val = seq)
: ULong val ?

Parameters

• base: U8 val = seq

Returns

• ULong val ?

---

usize [Src]

fun box usize(
  base: U8 val = seq)
: USize val ?

Parameters

• base: U8 val = seq

Returns

• USize val ?

---

read_int [Src] [A: ((I8 val | I16 val | I32 val | I64 val | I128 val | ILong val | ISize val | U8 val | U16 val | U32 val | U64 val | U128 val | ULong val | USize val) & Integer[A] val)]

Read an integer from the specified location in this string. The integer value read and the number of characters consumed are reported. The base parameter specifies the base to use, 0 indicates using the prefix, if any, to detect base 2, 10 or 16. If no integer is found at the specified location, then (0, 0) is returned, since no characters have been used. An integer out of range for the target type throws an error. A leading minus is allowed for signed integer types. Underscore characters are allowed throughout the integer and are ignored.

fun box read_int[A: ((I8 val | I16 val | I32 val | 
    I64 val | I128 val | ILong val | 
    ISize val | U8 val | U16 val | 
    U32 val | U64 val | U128 val | 
    ULong val | USize val) & Integer[A] val)](
  offset: ISize val = seq,
  base: U8 val = seq)
: (A , USize val) ?

Parameters

• offset: ISize val = seq
• base: U8 val = seq

Returns

• (A , USize val) ?

---

f32 [Src]

fun box f32(
  offset: ISize val = seq)
: F32 val

Parameters

• offset: ISize val = seq

Returns

• F32 val

---

f64 [Src]

fun box f64(
  offset: ISize val = seq)
: F64 val

Parameters

• offset: ISize val = seq

Returns

• F64 val

---

hash [Src]

fun box hash()
: U64 val

Returns

• U64 val

---

string [Src]

fun box string()
: String iso^

Returns

• String iso^

---

values [Src]

Return an iterator over the bytes in the string.

fun box values()
: StringBytes ref^

Returns

• StringBytes ref^

---

runes [Src]

Return an iterator over the codepoints in the string.

fun box runes()
: StringRunes ref^

Returns

• StringRunes ref^

---

ge

fun box ge(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---

gt

fun box gt(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---

ne

fun box ne(
  that: String box)
: Bool val

Parameters

• that: String box

Returns

• Bool val

---