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v/examples/regex_example.v

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/**********************************************************************
* regex samples
*
* Copyright (c) 2019-2020 Dario Deledda. All rights reserved.
* Use of this source code is governed by an MIT license
* that can be found in the LICENSE file.
*
* This file contains a collection of regex samples
*
**********************************************************************/
import regex
/*
This simple function convert an HTML RGB value with 3 or 6 hex digits to an u32 value,
this function is not optimized and it si only for didatical purpose
example: #A0B0CC #A9F
*/
fn convert_html_rgb(in_col string) u32 {
mut n_digit := if in_col.len == 4 { 1 } else { 2 }
mut col_mul := if in_col.len == 4 { 4 } else { 0 }
// this is the regex query, it use the V string interpolation to customize the regex query
// NOTE: if you want use escaped code you must use the r"" (raw) strings,
// *** please remember that the V interpoaltion doesn't work on raw strings. ***
query:= "#([a-fA-F0-9]{$n_digit})([a-fA-F0-9]{$n_digit})([a-fA-F0-9]{$n_digit})"
mut re := regex.regex_opt(query) or { panic(err) }
start, end := re.match_string(in_col)
println("start: $start, end: $end")
mut res := u32(0)
if start >= 0 {
group_list := re.get_group_list()
r := ("0x" + in_col[group_list[0].start..group_list[0].end]).int() << col_mul
g := ("0x" + in_col[group_list[1].start..group_list[1].end]).int() << col_mul
b := ("0x" + in_col[group_list[2].start..group_list[2].end]).int() << col_mul
println("r: $r g: $g b: $b")
res = u32(r) << 16 | u32(g) << 8 | u32(b)
}
return res
}
/*
This function demostrate the use of the named groups
*/
fn convert_html_rgb_n(in_col string) u32 {
mut n_digit := if in_col.len == 4 { 1 } else { 2 }
mut col_mul := if in_col.len == 4 { 4 } else { 0 }
query:= "#(?P<red>[a-fA-F0-9]{$n_digit})(?P<green>[a-fA-F0-9]{$n_digit})(?P<blue>[a-fA-F0-9]{$n_digit})"
mut re := regex.regex_opt(query) or { panic(err) }
start, end := re.match_string(in_col)
println("start: $start, end: $end")
mut res := u32(0)
if start >= 0 {
red_s, red_e := re.get_group("red")
r := ("0x" + in_col[red_s..red_e]).int() << col_mul
green_s, green_e := re.get_group("green")
g := ("0x" + in_col[green_s..green_e]).int() << col_mul
blue_s, blue_e := re.get_group("blue")
b := ("0x" + in_col[blue_s..blue_e]).int() << col_mul
println("r: $r g: $g b: $b")
res = u32(r) << 16 | u32(g) << 8 | u32(b)
}
return res
}
fn main() {
// convert HTML rgb color usign groups
println(convert_html_rgb("#A0b0Cc").hex())
println(convert_html_rgb("#ABC").hex())
// convert HTML rgb color using maned groups
println(convert_html_rgb_n("#A0B0CC").hex())
println(convert_html_rgb_n("#ABC").hex())
}