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This module contains support for a rope data type. Ropes can represent very long strings efficiently; in particular, concatenation is done in O(1) instead of O(n). They are essentially concatenation trees that are only flattened when converting to a native Nim string. The empty string is represented by nil. Ropes are immutable and subtrees can be shared without copying. Leaves can be cached for better memory efficiency at the cost of runtime efficiency.

Imports

streams

Types

Rope {.acyclic.} = ref object

A rope data type. The empty rope is represented by nil. Source Edit

Procs

proc `$`(r: Rope): string {....gcsafe, extern: "nroToString", raises: [], tags: [],
                            forbids: [].}

Converts a rope back to a string. Source Edit

proc `%`(frmt: string; args: openArray[Rope]): Rope {....gcsafe,
    extern: "nroFormat", raises: [ValueError], tags: [], forbids: [].}

% substitution operator for ropes. Does not support the $identifier nor ${identifier} notations.

Example:

let r1 = "$1 $2 $3" % [rope("Nim"), rope("is"), rope("a great language")]
doAssert $r1 == "Nim is a great language"
let r2 = "$# $# $#" % [rope("Nim"), rope("is"), rope("a great language")]
doAssert $r2 == "Nim is a great language"
let r3 = "${1} ${2} ${3}" % [rope("Nim"), rope("is"), rope("a great language")]
doAssert $r3 == "Nim is a great language"

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proc `&`(a, b: Rope): Rope {....gcsafe, extern: "nroConcRopeRope", raises: [],
                             tags: [], forbids: [].}

The concatenation operator for ropes.

Example:

let r = rope("Hello, ") & rope("Nim!")
doAssert $r == "Hello, Nim!"

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proc `&`(a: openArray[Rope]): Rope {....gcsafe, extern: "nroConcOpenArray",
                                     raises: [], tags: [], forbids: [].}

The concatenation operator for an openArray of ropes.

Example:

let r = &[rope("Hello, "), rope("Nim"), rope("!")]
doAssert $r == "Hello, Nim!"

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proc `&`(a: Rope; b: string): Rope {....gcsafe, extern: "nroConcRopeStr",
                                     raises: [], tags: [], forbids: [].}

The concatenation operator for ropes.

Example:

let r = rope("Hello, ") & "Nim!"
doAssert $r == "Hello, Nim!"

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proc `&`(a: string; b: Rope): Rope {....gcsafe, extern: "nroConcStrRope",
                                     raises: [], tags: [], forbids: [].}

The concatenation operator for ropes.

Example:

let r = "Hello, " & rope("Nim!")
doAssert $r == "Hello, Nim!"

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proc `[]`(r: Rope; i: int): char {....gcsafe, extern: "nroCharAt", raises: [],
                                   tags: [], forbids: [].}

Returns the character at position i in the rope r. This is quite expensive! Worst-case: O(n). If i >= r.len or i < 0, \0 is returned.

Example:

let r = rope("Hello, Nim!")
doAssert r[0] == 'H'
doAssert r[7] == 'N'
doAssert r[22] == '\0'

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proc add(a: var Rope; b: Rope) {....gcsafe, extern: "nro$1Rope", raises: [],
                                 tags: [], forbids: [].}

Adds b to the rope a.

Example:

var r = rope("Hello, ")
r.add(rope("Nim!"))
doAssert $r == "Hello, Nim!"

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proc add(a: var Rope; b: string) {....gcsafe, extern: "nro$1Str", raises: [],
                                   tags: [], forbids: [].}

Adds b to the rope a.

Example:

var r = rope("Hello, ")
r.add("Nim!")
doAssert $r == "Hello, Nim!"

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proc addf(c: var Rope; frmt: string; args: openArray[Rope]) {....gcsafe,
    extern: "nro$1", raises: [ValueError], tags: [], forbids: [].}

Shortcut for add(c, frmt % args).

Example:

var r = rope("Dash: ")
r.addf "$1 $2 $3", [rope("Nim"), rope("is"), rope("a great language")]
doAssert $r == "Dash: Nim is a great language"

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proc disableCache() {....gcsafe, extern: "nro$1", raises: [], tags: [], forbids: [].}

The cache is discarded and disabled. The GC will reuse its used memory. Source Edit

proc enableCache() {....gcsafe, extern: "nro$1", raises: [], tags: [], forbids: [].}

Enables the caching of leaves. This reduces the memory footprint at the cost of runtime efficiency. Source Edit

proc equalsFile(r: Rope; f: File): bool {....gcsafe, extern: "nro$1File",
    raises: [IOError], tags: [ReadIOEffect], forbids: [].}

Returns true if the contents of the file f equal r. Source Edit

proc equalsFile(r: Rope; filename: string): bool {....gcsafe, extern: "nro$1Str",
    raises: [IOError], tags: [ReadIOEffect], forbids: [].}

Returns true if the contents of the file f equal r. If f does not exist, false is returned. Source Edit

proc len(a: Rope): int {....gcsafe, extern: "nro$1", raises: [], tags: [],
                         forbids: [].}

The rope’s length. Source Edit

proc rope(f: BiggestFloat): Rope {....gcsafe, extern: "nro$1BiggestFloat",
                                   raises: [], tags: [], forbids: [].}

Converts a float to a rope.

Example:

let r = rope(4.29)
doAssert $r == "4.29"

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proc rope(i: BiggestInt): Rope {....gcsafe, extern: "nro$1BiggestInt", raises: [],
                                 tags: [], forbids: [].}

Converts an int to a rope.

Example:

let r = rope(429)
doAssert $r == "429"

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proc rope(s: string = ""): Rope {....gcsafe, extern: "nro$1Str", raises: [],
                                  tags: [], forbids: [].}

Converts a string to a rope.

Example:

let r = rope("I'm a rope")
doAssert $r == "I'm a rope"

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proc write(f: File; r: Rope) {....gcsafe, extern: "nro$1", raises: [IOError],
                               tags: [WriteIOEffect], forbids: [].}

Writes a rope to a file. Source Edit

proc write(s: Stream; r: Rope) {....gcsafe, extern: "nroWriteStream",
                                 raises: [IOError, OSError],
                                 tags: [WriteIOEffect], forbids: [].}

Writes a rope to a stream. Source Edit

Iterators

iterator items(r: Rope): char {....raises: [], tags: [], forbids: [].}

Iterates over any character in the rope r. Source Edit

iterator leaves(r: Rope): string {....raises: [], tags: [], forbids: [].}

Iterates over any leaf string in the rope r.

Example:

let r = rope("Hello") & rope(", Nim!")
let s = ["Hello", ", Nim!"]
var index = 0
for leave in r.leaves:
  doAssert leave == s[index]
  inc(index)

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