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authorIndrajith K L2022-12-03 17:00:20 +0530
committerIndrajith K L2022-12-03 17:00:20 +0530
commitf5c4671bfbad96bf346bd7e9a21fc4317b4959df (patch)
tree2764fc62da58f2ba8da7ed341643fc359873142f /v_windows/v/old/examples/regex/regex_with_memoization.v
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Adds most of the toolsHEADmaster
Diffstat (limited to 'v_windows/v/old/examples/regex/regex_with_memoization.v')
-rw-r--r--v_windows/v/old/examples/regex/regex_with_memoization.v127
1 files changed, 127 insertions, 0 deletions
diff --git a/v_windows/v/old/examples/regex/regex_with_memoization.v b/v_windows/v/old/examples/regex/regex_with_memoization.v
new file mode 100644
index 0000000..28e346b
--- /dev/null
+++ b/v_windows/v/old/examples/regex/regex_with_memoization.v
@@ -0,0 +1,127 @@
+import os
+
+fn regex_match(src string, pat string) bool {
+ src_size := src.len + 1
+ pat_size := pat.len + 1
+ mut memo := [][]int{len: src_size, init: []int{len: pat_size, init: -1}}
+ return regex_match_core(src, pat, 0, 0, mut memo)
+}
+
+fn regex_match_core(src string, pat string, src_pos int, pat_pos int, mut memo [][]int) bool {
+ if memo[src_pos][pat_pos] != -1 {
+ return memo[src_pos][pat_pos] == 1
+ }
+ mut spos := src_pos
+ mut ppos := pat_pos
+ if spos >= src.len && ppos >= pat.len {
+ memo[src_pos][pat_pos] = 1
+ return true
+ } else if spos < src.len && ppos >= pat.len {
+ memo[src_pos][pat_pos] = 0
+ return false
+ } else if spos >= src.len && ppos < pat.len {
+ if pat[ppos] == `\\` {
+ ppos++
+ }
+ res := ppos + 1 < pat.len && pat[ppos + 1] in [`*`, `?`]
+ && regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else {
+ first_is_bslash := pat[ppos] == `\\`
+ if first_is_bslash {
+ ppos++
+ }
+ first_bslash_and_match := first_is_bslash && ppos < pat.len
+ && (((pat[ppos] == `d` && src[spos].is_digit())
+ || (pat[ppos] == `D` && !src[spos].is_digit())
+ || (pat[ppos] == `s` && src[spos].is_space())
+ || (pat[ppos] == `S` && !src[spos].is_space())
+ || (pat[ppos] == `w` && (src[spos].is_digit() || src[spos].is_letter()
+ || src[spos] == `_`)) || (pat[ppos] == `W` && !(src[spos].is_digit()
+ || src[spos].is_letter() || src[spos] == `_`)))
+ || (pat[ppos] in [`d`, `D`, `s`, `S`, `w`, `W`] && ppos + 1 < pat.len
+ && pat[ppos + 1] in [`*`, `?`, `+`])
+ || (pat[ppos] !in [`d`, `D`, `s`, `S`, `w`, `W`] && src[spos] == pat[ppos]))
+ if ppos + 1 < pat.len {
+ match pat[ppos + 1] {
+ `*` {
+ if first_bslash_and_match {
+ res := regex_match_core(src, pat, spos + 1, ppos - 1, mut memo)
+ || regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else if src[spos] == pat[ppos] || pat[ppos] == `.` {
+ res := regex_match_core(src, pat, spos + 1, ppos, mut memo)
+ || regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else {
+ res := regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ }
+ }
+ `+` {
+ if first_bslash_and_match {
+ res := regex_match_core(src, pat, spos + 1, ppos - 1, mut memo)
+ || regex_match_core(src, pat, spos + 1, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else if src[spos] == pat[ppos] || pat[ppos] == `.` {
+ res := regex_match_core(src, pat, spos + 1, ppos, mut memo)
+ || regex_match_core(src, pat, spos + 1, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else {
+ memo[src_pos][pat_pos] = 0
+ return false
+ }
+ }
+ `?` {
+ if first_bslash_and_match || src[spos] == pat[ppos] || pat[ppos] == `.` {
+ res := regex_match_core(src, pat, spos + 1, ppos + 2, mut memo)
+ || regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else {
+ res := regex_match_core(src, pat, spos, ppos + 2, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ }
+ }
+ else {}
+ }
+ }
+ if first_is_bslash {
+ res := first_bslash_and_match
+ && regex_match_core(src, pat, spos + 1, ppos + 1, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ } else {
+ res := (src[spos] == pat[ppos] || pat[ppos] == `.`) && pat[ppos] != `\\`
+ && regex_match_core(src, pat, spos + 1, ppos + 1, mut memo)
+ memo[src_pos][pat_pos] = if res { 1 } else { 0 }
+ return res
+ }
+ }
+}
+
+fn main() {
+ mut cnt := 0
+ println('currently supported patterns: . ? + * \\ \\d \\D \\s \\S \\w \\W')
+ println('example: source `address@domain.net` matches pattern `\\w+@domain\\.net`')
+ println('enter `exit` to quit\n')
+ for {
+ cnt++
+ src := os.input('[$cnt] enter source string: ')
+ if src == 'exit' {
+ break
+ }
+ pat := os.input('[$cnt] enter pattern string: ')
+ if pat == 'exit' {
+ break
+ }
+ println('[$cnt] whether `$src` matches `$pat`: ${regex_match(src, pat)}')
+ }
+}