String [Source] A String is an ordered collection of bytes. 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 [Source] An empty string. Enough space for len bytes is reserved. new ref create(
  len: USize val = 0)
: String ref^
 Parameters  len: USize val = 0  Returns  
String ref^  from_array [Source] 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 [Source] 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 [Source] 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 = 0)
: String ref^
 Parameters  str: Pointer[U8 val] ref len: USize val alloc: USize val = 0  Returns  
String ref^  from_cstring [Source] 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 [Source] 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 [Source] 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 [Source] 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 [Source] Push a UTF-32 code point. fun ref push_utf32(
  value: U32 val)
: None val
 Parameters  value: U32 val  Returns  
None val  cpointer [Source] Returns a C compatible pointer to the underlying string allocation. fun box cpointer(
  offset: USize val = 0)
: Pointer[U8 val] tag
 Parameters  offset: USize val = 0  Returns  
Pointer[U8 val] tag  cstring [Source] 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 [Source] Returns an Array[U8] that reuses the underlying data pointer. fun val array()
: Array[U8 val] val
 Returns  
Array[U8 val] val  iso_array [Source] Returns an Array[U8] iso that reuses the underlying data pointer. fun iso iso_array()
: Array[U8 val] iso^
 Returns  
Array[U8 val] iso^  size [Source] Returns the length of the string data in bytes. fun box size()
: USize val
 Returns  
USize val  codepoints [Source] 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 = 0,
  to: ISize val = call)
: USize val
 Parameters  from: ISize val = 0 to: ISize val = call  Returns  
USize val  space [Source] Returns the space available for data, not including the null terminator. fun box space()
: USize val
 Returns  
USize val  reserve [Source] 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 [Source] 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 [Source] 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 [Source] 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 [Source] 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 = 0,
  to: USize val = call)
: None val
 Parameters  from: USize val = 0 to: USize val = call  Returns  
None val  trim [Source] 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 = 0,
  to: USize val = call)
: String val
 Parameters  from: USize val = 0 to: USize val = call  Returns  
String val  chop [Source] Chops the string in half at the split point requested and returns both the left and right portions. The original string is trimmed in place and returned as the left portion. If the split point is larger than the string, the left portion is the original string and the right portion is a new empty string. Both strings are isolated and mutable, as they do not share memory. The operation does not allocate a new string pointer nor copy elements. fun iso chop(
  split_point: USize val)
: (String iso^ , String iso^)
 Parameters  split_point: USize val  Returns  (String iso^ , String iso^)  unchop [Source] Unchops two iso strings to return the original string they were chopped from. Both input strings are isolated and mutable and were originally chopped from a single string. This function checks that they are indeed two strings chopped from the same original string and can be unchopped before doing the unchopping and returning the unchopped string. If the two strings cannot be unchopped it returns both strings without modifying them. The operation does not allocate a new string pointer nor copy elements. fun iso unchop(
  b: String iso)
: ((String iso^ , String iso^) | String iso^)
 Parameters  b: String iso  Returns  ((String iso^ , String iso^) | String iso^)  is_null_terminated [Source] 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 [Source] 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 [Source] 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 [Source] 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 [Source] 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 [Source] 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 [Source] 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^  repeat_str [Source] Returns a copy of the string repeated num times with an optional separator added inbetween repeats. fun box repeat_str(
  num: USize val = 1,
  sep: String val = "")
: String iso^
 Parameters  num: USize val = 1 sep: String val = ""  Returns  
String iso^  mul [Source] Returns a copy of the string repeated num times. fun box mul(
  num: USize val)
: String iso^
 Parameters  num: USize val  Returns  
String iso^  find [Source] 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 = 0,
  nth: USize val = 0)
: ISize val ?
 Parameters  s: String box offset: ISize val = 0 nth: USize val = 0  Returns  
ISize val ?  rfind [Source] 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 = call,
  nth: USize val = 0)
: ISize val ?
 Parameters  s: String box offset: ISize val = call nth: USize val = 0  Returns  
ISize val ?  contains [Source] Returns true if contains s as a substring, false otherwise. fun box contains(
  s: String box,
  offset: ISize val = 0,
  nth: USize val = 0)
: Bool val
 Parameters  s: String box offset: ISize val = 0 nth: USize val = 0  Returns  
Bool val  count [Source] Counts the non-overlapping occurrences of s in the string. fun box count(
  s: String box,
  offset: ISize val = 0)
: USize val
 Parameters  s: String box offset: ISize val = 0  Returns  
USize val  at [Source] Returns true if the substring s is present at the given offset. fun box at(
  s: String box,
  offset: ISize val = 0)
: Bool val
 Parameters  s: String box offset: ISize val = 0  Returns  
Bool val  delete [Source] Delete len bytes at the supplied offset, compacting the string in place. fun ref delete(
  offset: ISize val,
  len: USize val = 1)
: None val
 Parameters  offset: ISize val len: USize val = 1  Returns  
None val  substring [Source] 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 = call)
: String iso^
 Parameters  from: ISize val to: ISize val = call  Returns  
String iso^  lower [Source] Returns a lower case version of the string. fun box lower()
: String iso^
 Returns  
String iso^  lower_in_place [Source] Transforms the string to lower case. Currently only knows ASCII case. fun ref lower_in_place()
: None val
 Returns  
None val  upper [Source] Returns an upper case version of the string. Currently only knows ASCII case. fun box upper()
: String iso^
 Returns  
String iso^  upper_in_place [Source] Transforms the string to upper case. fun ref upper_in_place()
: None val
 Returns  
None val  reverse [Source] Returns a reversed version of the string. fun box reverse()
: String iso^
 Returns  
String iso^  reverse_in_place [Source] 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 [Source] 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 [Source] Remove a byte from the end of the string. fun ref pop()
: U8 val ?
 Returns  
U8 val ?  unshift [Source] 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 [Source] Removes a byte from the beginning of the string. fun ref shift()
: U8 val ?
 Returns  
U8 val ?  append [Source] Append the elements from a sequence, starting from the given offset. fun ref append(
  seq: ReadSeq[U8 val] box,
  offset: USize val = 0,
  len: USize val = call)
: None val
 Parameters  seq: ReadSeq[U8 val] box offset: USize val = 0 len: USize val = call  Returns  
None val  concat [Source] 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 = 0,
  len: USize val = call)
: None val
 Parameters  iter: Iterator[U8 val] ref offset: USize val = 0 len: USize val = call  Returns  
None val  clear [Source] Truncate the string to zero length. fun ref clear()
: None val
 Returns  
None val  insert [Source] 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 [Source] 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 [Source] 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 [Source] 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 = call)
: String iso^
 Parameters  from: ISize val to: ISize val = call  Returns  
String iso^  cut_in_place [Source] 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 = call)
: None val
 Parameters  from: ISize val to: ISize val = call  Returns  
None val  remove [Source] 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 [Source] 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 = 0)
: USize val
 Parameters  from: String box to: String box n: USize val = 0  Returns  
USize val  split_by [Source] 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. Example: let original: String = "<b><span>Hello!</span></b>"
let delimiter: String = "><"
let split_array: Array[String] = original.split_by(delimiter)
env.out.print("OUTPUT:")
for value in split_array.values() do
  env.out.print(value)
end

// OUTPUT:
// <b
// span>Hello!</span
// b>
 Adjacent delimiters result in a zero length entry in the array. For example, "1CutCut2".split_by("Cut") => ["1", "", "2"]. An empty delimiter results in an array that contains a single element equal to the whole string. If you want to split the string with each individual character of delim, use split. fun box split_by(
  delim: String val,
  n: USize val = call)
: Array[String val] iso^
 Parameters  delim: String val n: USize val = call  Returns  
Array[String val] iso^  split [Source] Split the string into an array of strings with any character in the delimiter string. By default, the string is split with whitespace characters. If n > 0, then the split count is limited to n. Example: let original: String = "name,job;department"
let delimiter: String = ".,;"
let split_array: Array[String] = original.split(delimiter)
env.out.print("OUTPUT:")
for value in split_array.values() do
  env.out.print(value)
end

// OUTPUT:
// name
// job
// department
 Adjacent delimiters result in a zero length entry in the array. For example, "1,,2".split(",") => ["1", "", "2"]. If you want to split the string with the entire delimiter string delim, use split_by. fun box split(
  delim: String val = "     
",
  n: USize val = 0)
: Array[String val] iso^
 Parameters  delim: String val = " " n: USize val = 0  Returns  
Array[String val] iso^  strip [Source] Remove all leading and trailing characters from the string that are in s. fun ref strip(
  s: String box = "     
")
: None val
 Parameters  s: String box = " "  Returns  
None val  rstrip [Source] Remove all trailing characters within the string that are in s. By default, trailing whitespace is removed. fun ref rstrip(
  s: String box = "     
")
: None val
 Parameters  s: String box = " "  Returns  
None val  lstrip [Source] Remove all leading characters within the string that are in s. By default, leading whitespace is removed. fun ref lstrip(
  s: String box = "     
")
: None val
 Parameters  s: String box = " "  Returns  
None val  add [Source] 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 [Source] 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 [Source] 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 [Source] 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 = 0,
  that_offset: ISize val = 0,
  ignore_case: Bool val = false)
: (Less val | Equal val | Greater val)
 Parameters  that: String box n: USize val offset: ISize val = 0 that_offset: ISize val = 0 ignore_case: Bool val = false  Returns  (Less val | Equal val | Greater val)  eq [Source] 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 [Source] 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 [Source] 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 [Source] fun box offset_to_index(
  i: ISize val)
: USize val
 Parameters  i: ISize val  Returns  
USize val  bool [Source] fun box bool()
: Bool val ?
 Returns  
Bool val ?  i8 [Source] fun box i8(
  base: U8 val = 0)
: I8 val ?
 Parameters  base: U8 val = 0  Returns  
I8 val ?  i16 [Source] fun box i16(
  base: U8 val = 0)
: I16 val ?
 Parameters  base: U8 val = 0  Returns  
I16 val ?  i32 [Source] fun box i32(
  base: U8 val = 0)
: I32 val ?
 Parameters  base: U8 val = 0  Returns  
I32 val ?  i64 [Source] fun box i64(
  base: U8 val = 0)
: I64 val ?
 Parameters  base: U8 val = 0  Returns  
I64 val ?  i128 [Source] fun box i128(
  base: U8 val = 0)
: I128 val ?
 Parameters  base: U8 val = 0  Returns  
I128 val ?  ilong [Source] fun box ilong(
  base: U8 val = 0)
: ILong val ?
 Parameters  base: U8 val = 0  Returns  
ILong val ?  isize [Source] fun box isize(
  base: U8 val = 0)
: ISize val ?
 Parameters  base: U8 val = 0  Returns  
ISize val ?  u8 [Source] fun box u8(
  base: U8 val = 0)
: U8 val ?
 Parameters  base: U8 val = 0  Returns  
U8 val ?  u16 [Source] fun box u16(
  base: U8 val = 0)
: U16 val ?
 Parameters  base: U8 val = 0  Returns  
U16 val ?  u32 [Source] fun box u32(
  base: U8 val = 0)
: U32 val ?
 Parameters  base: U8 val = 0  Returns  
U32 val ?  u64 [Source] fun box u64(
  base: U8 val = 0)
: U64 val ?
 Parameters  base: U8 val = 0  Returns  
U64 val ?  u128 [Source] fun box u128(
  base: U8 val = 0)
: U128 val ?
 Parameters  base: U8 val = 0  Returns  
U128 val ?  ulong [Source] fun box ulong(
  base: U8 val = 0)
: ULong val ?
 Parameters  base: U8 val = 0  Returns  
ULong val ?  usize [Source] fun box usize(
  base: U8 val = 0)
: USize val ?
 Parameters  base: U8 val = 0  Returns  
USize val ?  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)] [Source] Read an integer from the specified location in this string. The integer value read and the number of bytes 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 = 0,
  base: U8 val = 0)
: (A , USize val) ?
 Parameters  offset: ISize val = 0 base: U8 val = 0  Returns  (A , USize val) ?  f32 [Source] Convert this string starting at the given offset to a 32-bit floating point number (F32). This method errors if this string cannot be parsed to a float, if the result would over- or underflow, the offset exceeds the size of this string or there are leftover characters in the string after conversion. Examples: "1.5".f32()? == F32(1.5)
"1.19208e-07".f32()? == F32(1.19208e-07)
"NaN".f32()?.nan() == true
 fun box f32(
  offset: ISize val = 0)
: F32 val ?
 Parameters  offset: ISize val = 0  Returns  
F32 val ?  f64 [Source] Convert this string starting at the given offset to a 64-bit floating point number (F64). This method errors if this string cannot be parsed to a float, if the result would over- or underflow, the offset exceeds the size of this string or there are leftover characters in the string after conversion. Examples: "1.5".f64()? == F64(1.5)
"1.19208e-07".f64()? == F64(1.19208e-07)
"Inf".f64()?.infinite() == true
 fun box f64(
  offset: ISize val = 0)
: F64 val ?
 Parameters  offset: ISize val = 0  Returns  
F64 val ?  hash [Source] fun box hash()
: USize val
 Returns  
USize val  hash64 [Source] fun box hash64()
: U64 val
 Returns  
U64 val  string [Source] fun box string()
: String iso^
 Returns  
String iso^  values [Source] Return an iterator over the bytes in the string. fun box values()
: StringBytes ref^
 Returns  
StringBytes ref^  runes [Source] 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 

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