549 lines
16 KiB
Go
549 lines
16 KiB
Go
// Copyright 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package ext contains CEL extension libraries where each library defines a related set of
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// constants, functions, macros, or other configuration settings which may not be covered by
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// the core CEL spec.
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package ext
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import (
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"fmt"
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"strings"
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"unicode"
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"github.com/google/cel-go/cel"
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"github.com/google/cel-go/checker/decls"
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"github.com/google/cel-go/common/types"
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"github.com/google/cel-go/common/types/ref"
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"github.com/google/cel-go/interpreter/functions"
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exprpb "google.golang.org/genproto/googleapis/api/expr/v1alpha1"
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)
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// Strings returns a cel.EnvOption to configure extended functions for string manipulation.
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// As a general note, all indices are zero-based.
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//
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// CharAt
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//
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// Returns the character at the given position. If the position is negative, or greater than
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// the length of the string, the function will produce an error:
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//
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// <string>.charAt(<int>) -> <string>
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//
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// Examples:
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//
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// 'hello'.charAt(4) // return 'o'
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// 'hello'.charAt(5) // return ''
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// 'hello'.charAt(-1) // error
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//
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// IndexOf
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//
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// Returns the integer index of the first occurrence of the search string. If the search string is
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// not found the function returns -1.
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//
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// The function also accepts an optional position from which to begin the substring search. If the
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// substring is the empty string, the index where the search starts is returned (zero or custom).
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//
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// <string>.indexOf(<string>) -> <int>
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// <string>.indexOf(<string>, <int>) -> <int>
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//
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// Examples:
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//
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// 'hello mellow'.indexOf('') // returns 0
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// 'hello mellow'.indexOf('ello') // returns 1
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// 'hello mellow'.indexOf('jello') // returns -1
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// 'hello mellow'.indexOf('', 2) // returns 2
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// 'hello mellow'.indexOf('ello', 2) // returns 7
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// 'hello mellow'.indexOf('ello', 20) // error
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//
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// Join
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//
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// Returns a new string where the elements of string list are concatenated.
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//
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// The function also accepts an optional separator which is placed between elements in the resulting string.
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//
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// <list<string>>.join() -> <string>
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// <list<string>>.join(<string>) -> <string>
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//
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// Examples:
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//
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// ['hello', 'mellow'].join() // returns 'hellomellow'
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// ['hello', 'mellow'].join(' ') // returns 'hello mellow'
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// [].join() // returns ''
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// [].join('/') // returns ''
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//
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// LastIndexOf
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//
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// Returns the integer index at the start of the last occurrence of the search string. If the
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// search string is not found the function returns -1.
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//
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// The function also accepts an optional position which represents the last index to be
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// considered as the beginning of the substring match. If the substring is the empty string,
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// the index where the search starts is returned (string length or custom).
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//
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// <string>.lastIndexOf(<string>) -> <int>
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// <string>.lastIndexOf(<string>, <int>) -> <int>
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//
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// Examples:
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//
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// 'hello mellow'.lastIndexOf('') // returns 12
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// 'hello mellow'.lastIndexOf('ello') // returns 7
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// 'hello mellow'.lastIndexOf('jello') // returns -1
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// 'hello mellow'.lastIndexOf('ello', 6) // returns 1
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// 'hello mellow'.lastIndexOf('ello', -1) // error
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//
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// LowerAscii
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//
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// Returns a new string where all ASCII characters are lower-cased.
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//
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// This function does not perform Unicode case-mapping for characters outside the ASCII range.
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//
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// <string>.lowerAscii() -> <string>
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//
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// Examples:
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//
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// 'TacoCat'.lowerAscii() // returns 'tacocat'
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// 'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
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//
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// Replace
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//
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// Returns a new string based on the target, which replaces the occurrences of a search string
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// with a replacement string if present. The function accepts an optional limit on the number of
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// substring replacements to be made.
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//
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// When the replacement limit is 0, the result is the original string. When the limit is a negative
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// number, the function behaves the same as replace all.
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//
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// <string>.replace(<string>, <string>) -> <string>
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// <string>.replace(<string>, <string>, <int>) -> <string>
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//
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// Examples:
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//
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// 'hello hello'.replace('he', 'we') // returns 'wello wello'
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// 'hello hello'.replace('he', 'we', -1) // returns 'wello wello'
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// 'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
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// 'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
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//
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// Split
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//
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// Returns a list of strings split from the input by the given separator. The function accepts
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// an optional argument specifying a limit on the number of substrings produced by the split.
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//
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// When the split limit is 0, the result is an empty list. When the limit is 1, the result is the
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// target string to split. When the limit is a negative number, the function behaves the same as
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// split all.
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//
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// <string>.split(<string>) -> <list<string>>
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// <string>.split(<string>, <int>) -> <list<string>>
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//
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// Examples:
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//
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// 'hello hello hello'.split(' ') // returns ['hello', 'hello', 'hello']
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// 'hello hello hello'.split(' ', 0) // returns []
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// 'hello hello hello'.split(' ', 1) // returns ['hello hello hello']
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// 'hello hello hello'.split(' ', 2) // returns ['hello', 'hello hello']
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// 'hello hello hello'.split(' ', -1) // returns ['hello', 'hello', 'hello']
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//
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// Substring
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//
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// Returns the substring given a numeric range corresponding to character positions. Optionally
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// may omit the trailing range for a substring from a given character position until the end of
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// a string.
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//
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// Character offsets are 0-based with an inclusive start range and exclusive end range. It is an
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// error to specify an end range that is lower than the start range, or for either the start or end
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// index to be negative or exceed the string length.
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//
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// <string>.substring(<int>) -> <string>
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// <string>.substring(<int>, <int>) -> <string>
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//
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// Examples:
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//
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// 'tacocat'.substring(4) // returns 'cat'
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// 'tacocat'.substring(0, 4) // returns 'taco'
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// 'tacocat'.substring(-1) // error
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// 'tacocat'.substring(2, 1) // error
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//
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// Trim
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//
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// Returns a new string which removes the leading and trailing whitespace in the target string.
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// The trim function uses the Unicode definition of whitespace which does not include the
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// zero-width spaces. See: https://en.wikipedia.org/wiki/Whitespace_character#Unicode
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//
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// <string>.trim() -> <string>
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//
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// Examples:
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//
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// ' \ttrim\n '.trim() // returns 'trim'
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//
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// UpperAscii
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//
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// Returns a new string where all ASCII characters are upper-cased.
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//
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// This function does not perform Unicode case-mapping for characters outside the ASCII range.
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//
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// <string>.upperAscii() -> <string>
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//
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// Examples:
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//
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// 'TacoCat'.upperAscii() // returns 'TACOCAT'
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// 'TacoCÆt Xii'.upperAscii() // returns 'TACOCÆT XII'
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func Strings() cel.EnvOption {
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return cel.Lib(stringLib{})
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}
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type stringLib struct{}
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func (stringLib) CompileOptions() []cel.EnvOption {
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return []cel.EnvOption{
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cel.Declarations(
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decls.NewFunction("charAt",
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decls.NewInstanceOverload("string_char_at_int",
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[]*exprpb.Type{decls.String, decls.Int},
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decls.String)),
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decls.NewFunction("indexOf",
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decls.NewInstanceOverload("string_index_of_string",
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[]*exprpb.Type{decls.String, decls.String},
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decls.Int),
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decls.NewInstanceOverload("string_index_of_string_int",
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[]*exprpb.Type{decls.String, decls.String, decls.Int},
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decls.Int)),
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decls.NewFunction("lastIndexOf",
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decls.NewInstanceOverload("string_last_index_of_string",
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[]*exprpb.Type{decls.String, decls.String},
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decls.Int),
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decls.NewInstanceOverload("string_last_index_of_string_int",
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[]*exprpb.Type{decls.String, decls.String, decls.Int},
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decls.Int)),
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decls.NewFunction("lowerAscii",
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decls.NewInstanceOverload("string_lower_ascii",
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[]*exprpb.Type{decls.String},
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decls.String)),
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decls.NewFunction("replace",
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decls.NewInstanceOverload("string_replace_string_string",
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[]*exprpb.Type{decls.String, decls.String, decls.String},
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decls.String),
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decls.NewInstanceOverload("string_replace_string_string_int",
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[]*exprpb.Type{decls.String, decls.String, decls.String, decls.Int},
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decls.String)),
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decls.NewFunction("split",
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decls.NewInstanceOverload("string_split_string",
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[]*exprpb.Type{decls.String, decls.String},
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decls.NewListType(decls.String)),
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decls.NewInstanceOverload("string_split_string_int",
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[]*exprpb.Type{decls.String, decls.String, decls.Int},
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decls.NewListType(decls.String))),
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decls.NewFunction("substring",
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decls.NewInstanceOverload("string_substring_int",
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[]*exprpb.Type{decls.String, decls.Int},
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decls.String),
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decls.NewInstanceOverload("string_substring_int_int",
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[]*exprpb.Type{decls.String, decls.Int, decls.Int},
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decls.String)),
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decls.NewFunction("trim",
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decls.NewInstanceOverload("string_trim",
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[]*exprpb.Type{decls.String},
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decls.String)),
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decls.NewFunction("upperAscii",
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decls.NewInstanceOverload("string_upper_ascii",
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[]*exprpb.Type{decls.String},
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decls.String)),
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decls.NewFunction("join",
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decls.NewInstanceOverload("list_join",
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[]*exprpb.Type{decls.NewListType(decls.String)},
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decls.String),
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decls.NewInstanceOverload("list_join_string",
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[]*exprpb.Type{decls.NewListType(decls.String), decls.String},
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decls.String),
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),
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),
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}
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}
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func (stringLib) ProgramOptions() []cel.ProgramOption {
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wrappedReplace := callInStrStrStrOutStr(replace)
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wrappedReplaceN := callInStrStrStrIntOutStr(replaceN)
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return []cel.ProgramOption{
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cel.Functions(
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&functions.Overload{
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Operator: "charAt",
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Binary: callInStrIntOutStr(charAt),
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},
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&functions.Overload{
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Operator: "string_char_at_int",
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Binary: callInStrIntOutStr(charAt),
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},
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&functions.Overload{
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Operator: "indexOf",
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Binary: callInStrStrOutInt(indexOf),
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Function: callInStrStrIntOutInt(indexOfOffset),
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},
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&functions.Overload{
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Operator: "string_index_of_string",
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Binary: callInStrStrOutInt(indexOf),
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},
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&functions.Overload{
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Operator: "string_index_of_string_int",
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Function: callInStrStrIntOutInt(indexOfOffset),
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},
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&functions.Overload{
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Operator: "lastIndexOf",
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Binary: callInStrStrOutInt(lastIndexOf),
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Function: callInStrStrIntOutInt(lastIndexOfOffset),
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},
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&functions.Overload{
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Operator: "string_last_index_of_string",
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Binary: callInStrStrOutInt(lastIndexOf),
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},
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&functions.Overload{
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Operator: "string_last_index_of_string_int",
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Function: callInStrStrIntOutInt(lastIndexOfOffset),
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},
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&functions.Overload{
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Operator: "lowerAscii",
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Unary: callInStrOutStr(lowerASCII),
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},
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&functions.Overload{
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Operator: "string_lower_ascii",
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Unary: callInStrOutStr(lowerASCII),
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},
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&functions.Overload{
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Operator: "replace",
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Function: func(values ...ref.Val) ref.Val {
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if len(values) == 3 {
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return wrappedReplace(values...)
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}
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if len(values) == 4 {
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return wrappedReplaceN(values...)
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}
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return types.NoSuchOverloadErr()
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},
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},
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&functions.Overload{
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Operator: "string_replace_string_string",
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Function: wrappedReplace,
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},
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&functions.Overload{
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Operator: "string_replace_string_string_int",
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Function: wrappedReplaceN,
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},
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&functions.Overload{
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Operator: "split",
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Binary: callInStrStrOutListStr(split),
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Function: callInStrStrIntOutListStr(splitN),
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},
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&functions.Overload{
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Operator: "string_split_string",
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Binary: callInStrStrOutListStr(split),
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},
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&functions.Overload{
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Operator: "string_split_string_int",
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Function: callInStrStrIntOutListStr(splitN),
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},
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&functions.Overload{
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Operator: "substring",
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Binary: callInStrIntOutStr(substr),
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Function: callInStrIntIntOutStr(substrRange),
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},
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&functions.Overload{
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Operator: "string_substring_int",
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Binary: callInStrIntOutStr(substr),
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},
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&functions.Overload{
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Operator: "string_substring_int_int",
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Function: callInStrIntIntOutStr(substrRange),
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},
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&functions.Overload{
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Operator: "trim",
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Unary: callInStrOutStr(trimSpace),
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},
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&functions.Overload{
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Operator: "string_trim",
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Unary: callInStrOutStr(trimSpace),
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},
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&functions.Overload{
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Operator: "upperAscii",
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Unary: callInStrOutStr(upperASCII),
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},
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&functions.Overload{
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Operator: "string_upper_ascii",
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Unary: callInStrOutStr(upperASCII),
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},
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&functions.Overload{
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Operator: "join",
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Unary: callInListStrOutStr(join),
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Binary: callInListStrStrOutStr(joinSeparator),
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},
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&functions.Overload{
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Operator: "list_join",
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Unary: callInListStrOutStr(join),
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},
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&functions.Overload{
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Operator: "list_join_string",
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Binary: callInListStrStrOutStr(joinSeparator),
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},
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),
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}
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}
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func charAt(str string, ind int64) (string, error) {
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i := int(ind)
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runes := []rune(str)
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if i < 0 || i > len(runes) {
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return "", fmt.Errorf("index out of range: %d", ind)
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}
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if i == len(runes) {
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return "", nil
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}
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return string(runes[i]), nil
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}
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func indexOf(str, substr string) (int64, error) {
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return indexOfOffset(str, substr, int64(0))
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}
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func indexOfOffset(str, substr string, offset int64) (int64, error) {
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if substr == "" {
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return offset, nil
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}
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off := int(offset)
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runes := []rune(str)
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subrunes := []rune(substr)
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if off < 0 || off >= len(runes) {
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return -1, fmt.Errorf("index out of range: %d", off)
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}
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for i := off; i < len(runes)-(len(subrunes)-1); i++ {
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found := true
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for j := 0; j < len(subrunes); j++ {
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if runes[i+j] != subrunes[j] {
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found = false
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break
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}
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}
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if found {
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return int64(i), nil
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}
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}
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return -1, nil
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}
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func lastIndexOf(str, substr string) (int64, error) {
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runes := []rune(str)
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if substr == "" {
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return int64(len(runes)), nil
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}
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return lastIndexOfOffset(str, substr, int64(len(runes)-1))
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}
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func lastIndexOfOffset(str, substr string, offset int64) (int64, error) {
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if substr == "" {
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return offset, nil
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}
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off := int(offset)
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runes := []rune(str)
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subrunes := []rune(substr)
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if off < 0 || off >= len(runes) {
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return -1, fmt.Errorf("index out of range: %d", off)
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}
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if off > len(runes)-len(subrunes) {
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off = len(runes) - len(subrunes)
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}
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for i := off; i >= 0; i-- {
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found := true
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for j := 0; j < len(subrunes); j++ {
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if runes[i+j] != subrunes[j] {
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found = false
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break
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}
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}
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if found {
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return int64(i), nil
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}
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}
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return -1, nil
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}
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func lowerASCII(str string) (string, error) {
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runes := []rune(str)
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for i, r := range runes {
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if r <= unicode.MaxASCII {
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r = unicode.ToLower(r)
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runes[i] = r
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}
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}
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return string(runes), nil
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}
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func replace(str, old, new string) (string, error) {
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return strings.ReplaceAll(str, old, new), nil
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}
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func replaceN(str, old, new string, n int64) (string, error) {
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return strings.Replace(str, old, new, int(n)), nil
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}
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func split(str, sep string) ([]string, error) {
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return strings.Split(str, sep), nil
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}
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|
|
|
func splitN(str, sep string, n int64) ([]string, error) {
|
|
return strings.SplitN(str, sep, int(n)), nil
|
|
}
|
|
|
|
func substr(str string, start int64) (string, error) {
|
|
runes := []rune(str)
|
|
if int(start) < 0 || int(start) > len(runes) {
|
|
return "", fmt.Errorf("index out of range: %d", start)
|
|
}
|
|
return string(runes[start:]), nil
|
|
}
|
|
|
|
func substrRange(str string, start, end int64) (string, error) {
|
|
runes := []rune(str)
|
|
l := len(runes)
|
|
if start > end {
|
|
return "", fmt.Errorf("invalid substring range. start: %d, end: %d", start, end)
|
|
}
|
|
if int(start) < 0 || int(start) > l {
|
|
return "", fmt.Errorf("index out of range: %d", start)
|
|
}
|
|
if int(end) < 0 || int(end) > l {
|
|
return "", fmt.Errorf("index out of range: %d", end)
|
|
}
|
|
return string(runes[int(start):int(end)]), nil
|
|
}
|
|
|
|
func trimSpace(str string) (string, error) {
|
|
return strings.TrimSpace(str), nil
|
|
}
|
|
|
|
func upperASCII(str string) (string, error) {
|
|
runes := []rune(str)
|
|
for i, r := range runes {
|
|
if r <= unicode.MaxASCII {
|
|
r = unicode.ToUpper(r)
|
|
runes[i] = r
|
|
}
|
|
}
|
|
return string(runes), nil
|
|
}
|
|
|
|
func joinSeparator(strs []string, separator string) (string, error) {
|
|
return strings.Join(strs, separator), nil
|
|
}
|
|
|
|
func join(strs []string) (string, error) {
|
|
return strings.Join(strs, ""), nil
|
|
}
|