4 files changed, 160 insertions, 0 deletions
diff --git a/misc/examples/regularexpressions/regex1.c b/misc/examples/regularexpressions/regex1.c
new file mode 100644
index 00000000..d8032358
--- /dev/null
+++ b/misc/examples/regularexpressions/regex1.c
@@ -0,0 +1,32 @@
+#define i_import
+#include <stc/cregex.h>
+
+int main(int argc, char* argv[])
+{
+    if (argc <= 1) {
+        printf("Usage: regex1 -i\n");
+        return 0;
+    }
+    cstr input = {0};
+    cregex float_expr = {0};
+
+    int res = cregex_compile(&float_expr, "^[+-]?[0-9]+((\\.[0-9]*)?|\\.[0-9]+)$");
+    // Until "q" is given, ask for another number
+    if (res > 0) while (true)
+    {
+        printf("Enter a double precision number (q for quit): ");
+        cstr_getline(&input, stdin);
+
+        // Exit when the user inputs q
+        if (cstr_equals(&input, "q"))
+            break;
+
+        if (cregex_is_match(&float_expr, cstr_str(&input)))
+            printf("Input is a float\n");
+        else
+            printf("Invalid input : Not a float\n");
+    }
+
+    cstr_drop(&input);
+    cregex_drop(&float_expr);
+}
diff --git a/misc/examples/regularexpressions/regex2.c b/misc/examples/regularexpressions/regex2.c
new file mode 100644
index 00000000..a798b1a1
--- /dev/null
+++ b/misc/examples/regularexpressions/regex2.c
@@ -0,0 +1,34 @@
+#define i_import
+#include <stc/cregex.h>
+
+int main(void)
+{
+    struct { const char *pattern, *input; } s[] = {
+        {"(\\d\\d\\d\\d)[-_](1[0-2]|0[1-9])[-_](3[01]|[12][0-9]|0[1-9])",
+         "date: 2024-02-29 leapyear day, christmas eve is on 2022-12-24."
+        },
+        {"(https?://|ftp://|www\\.)([0-9A-Za-z@:%_+~#=-]+\\.)+([a-z][a-z][a-z]?)(/[/0-9A-Za-z\\.@:%_+~#=\\?&-]*)?",
+         "https://en.cppreference.com/w/cpp/regex/regex_search"
+        },
+        {"!((abc|123)+)!", "!123abcabc!"},
+        {"(\\p{Alpha}+ )+(\\p{Nd}+)", "Großpackung süßigkeiten 199"},
+        {"\\p{Han}+", "This is Han: 王明：那是杂志吗？"},
+    };
+
+    cregex re = {0};
+    c_forrange (i, c_arraylen(s))
+    {
+        int res = cregex_compile(&re, s[i].pattern);
+        if (res < 0) {
+            printf("error in regex pattern: %d\n", res);
+            continue;
+        }
+        printf("\ninput: %s\n", s[i].input);
+
+        c_formatch (j, &re, s[i].input) {
+            c_forrange (k, cregex_captures(&re) + 1)
+                printf("  submatch %lld: %.*s\n", k, c_SV(j.match[k]));
+        }
+    }
+    cregex_drop(&re);
+}
diff --git a/misc/examples/regularexpressions/regex_match.c b/misc/examples/regularexpressions/regex_match.c
new file mode 100644
index 00000000..9106ffbd
--- /dev/null
+++ b/misc/examples/regularexpressions/regex_match.c
@@ -0,0 +1,37 @@
+#define i_import
+#include <stc/cregex.h>
+#define i_implement
+#include <stc/csview.h>
+
+#define i_key float
+#include <stc/cstack.h>
+
+int main(void)
+{
+    // Lets find the first sequence of digits in a string
+    const char *str = "Hello numeric world, there are 24 hours in a day, 3600 seconds in an hour."
+                      " Around 365.25 days a year, and 52 weeks in a year."
+                      " Boltzmann const: 1.38064852E-23, is very small."
+                      " Bohrradius is 5.29177210903e-11, and Avogadros number is 6.02214076e23.";
+    cregex re = {0};
+    cstack_float vec = {0};
+
+    const char* pattern = "[+-]?([0-9]*\\.)?\\d+([Ee][+-]?\\d+)?";
+    int res = cregex_compile(&re, pattern);
+    printf("%d: %s\n", res, pattern);
+
+    // extract and convert all numbers in str to floats
+    c_formatch (i, &re, str)
+        cstack_float_push(&vec, (float)atof(i.match[0].buf));
+
+    c_foreach (i, cstack_float, vec)
+        printf("  %g\n", (double)*i.ref);
+
+    // extracts the numbers only to a comma separated string.
+    cstr nums = cregex_replace_sv(&re, csview_from(str), " $0,", 0, NULL, CREG_STRIP);
+    printf("\n%s\n", cstr_str(&nums));
+
+    cstr_drop(&nums);
+    cregex_drop(&re);
+    cstack_float_drop(&vec);
+}
diff --git a/misc/examples/regularexpressions/regex_replace.c b/misc/examples/regularexpressions/regex_replace.c
new file mode 100644
index 00000000..087387d7
--- /dev/null
+++ b/misc/examples/regularexpressions/regex_replace.c
@@ -0,0 +1,57 @@
+#define i_import
+#include <stc/cregex.h>
+#include <stc/csview.h>
+
+bool add_10_years(int i, csview match, cstr* out) {
+    if (i == 1) { // group 1 matches year
+        int year;
+        sscanf(match.buf, "%4d", &year); // scan 4 chars only
+        cstr_printf(out, "%04d", year + 10);
+        return true;
+    }
+    return false;
+}
+
+int main(void)
+{
+    const char* pattern = "\\b(\\d\\d\\d\\d)-(1[0-2]|0[1-9])-(3[01]|[12][0-9]|0[1-9])\\b";
+    const char* input = "start date: 2015-12-31, end date: 2022-02-28";
+    cstr str = {0};
+    cregex re = {0};
+
+    c_defer(
+        cregex_drop(&re),
+        cstr_drop(&str)
+    ){
+        printf("INPUT: %s\n", input);
+
+        /* replace with a fixed string, extended all-in-one call: */
+        cstr_take(&str, cregex_replace_pattern(pattern, input, "YYYY-MM-DD"));
+        printf("fixed: %s\n", cstr_str(&str));
+
+        /* US date format, and add 10 years to dates: */
+        cstr_take(&str, cregex_replace_pattern(pattern, input, "$1/$3/$2", 0, add_10_years, CREG_DEFAULT));
+        printf("us+10: %s\n", cstr_str(&str));
+
+        /* Wrap first date inside []: */
+        cstr_take(&str, cregex_replace_pattern(pattern, input, "[$0]"));
+        printf("brack: %s\n", cstr_str(&str));
+
+        /* Shows how to compile RE separately */
+        re = cregex_from(pattern);
+        if (cregex_captures(&re) == 0)
+            continue; /* break c_defer */
+
+        /* European date format. */
+        cstr_take(&str, cregex_replace(&re, input, "$3.$2.$1"));
+        printf("euros: %s\n", cstr_str(&str));
+
+        /* Strip out everything but the matches */
+        cstr_take(&str, cregex_replace_sv(&re, csview_from(input), "$3.$2.$1;", 0, NULL, CREG_STRIP));
+        printf("strip: %s\n", cstr_str(&str));
+
+        /* Wrap all words in ${} */
+        cstr_take(&str, cregex_replace_pattern("[a-z]+", "52 apples and 31 mangoes", "$${$0}"));
+        printf("curly: %s\n", cstr_str(&str));
+    }
+}