advances of the http server example; built-ins for generating random numbers; built-ins for slicing, trimming and converting strings to integers

src/lib/builtins/string.c

@@ -1,6 +1,8 @@
+#include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdint.h>
+#include "utils.h"
 #include "string.h"
 #include "../utils/defs.h"
 #include "../utils/utf8.h"
@@ -135,8 +137,138 @@ static int bin_cat(Runtime *runtime, Object **argv, unsigned int argc, Object *r
     return 1;
 }
 
+static int bin_slice(Runtime *runtime, Object **argv, unsigned int argc, Object *rets[static MAX_RETS], Error *error)
+{
+    // 0: string
+    // 1: start offset or none
+    // 2: end offset or none
+
+    ParsedArgument pargs[3];
+    if (!parseArgs(error, argv, argc, pargs, "s?i?i"))
+        return -1;
+
+    const char *srcstr = pargs[0].as_string.data;
+    size_t      srclen = pargs[0].as_string.size;
+
+    size_t offset;
+    size_t length;
+
+    if (pargs[1].defined) {
+        int64_t n = pargs[1].as_int;
+        if (n < 0) {
+            Error_Report(error, 0, "starting offset of string slice must be non-negative");
+            return -1;
+        }
+        offset = (size_t) n;
+    } else
+        offset = 0;
+
+    if (pargs[2].defined) {
+        int64_t n = pargs[2].as_int;
+        if (n < 0) {
+            Error_Report(error, 0, "length of string slice must be non-negative");
+            return -1;
+        }
+        length = (size_t) n;
+    } else
+        length = srclen - offset;
+
+    if (offset > srclen) {
+        Error_Report(error, 0, "string slice offset is out of bounds");
+        return -1;
+    }
+    if (offset + length > srclen) {
+        Error_Report(error, 0, "string slice length is out of bounds");
+        return -1;
+    }
+
+    Heap *heap = Runtime_GetHeap(runtime);
+    Object *slice = Object_FromString(srcstr + offset, length, heap, error);
+    if (slice == NULL)
+        return -1;
+    rets[0] = slice;
+    return 1;
+}
+
+static int bin_trim(Runtime *runtime, Object **argv, unsigned int argc, Object *rets[static MAX_RETS], Error *error)
+{
+    // 0: string
+
+    ParsedArgument pargs[1];
+    if (!parseArgs(error, argv, argc, pargs, "s"))
+        return -1;
+
+    const char *srcstr = pargs[0].as_string.data;
+    size_t      srclen = pargs[0].as_string.size;
+
+    size_t offset = 0;
+    size_t length = srclen;
+
+    while (offset < srclen && srcstr[offset] == ' ')
+        offset++;
+
+    Heap *heap = Runtime_GetHeap(runtime);
+
+    Object *result;
+    if (offset == srclen)
+        // The string only contained whitespace.
+        // Return an empty string.
+        result = Object_FromString("", 0, heap, error);
+    else {
+        
+        // NOTE: The string doesn't contain only
+        //       whitespace, so the length can't
+        //       go under 1.
+        while (srcstr[offset + length - 1] == ' ')
+            length--;
+
+        result = Object_FromString(srcstr + offset, length, heap, error);
+    }
+
+    if (result == NULL)
+        return -1;
+    rets[0] = result;
+    return 1;
+}
+
+static int bin_toInt(Runtime *runtime, Object **argv, unsigned int argc, Object *rets[static MAX_RETS], Error *error)
+{
+    // 0: string
+
+    ParsedArgument pargs[1];
+    if (!parseArgs(error, argv, argc, pargs, "s"))
+        return -1;
+
+    const char *srcstr = pargs[0].as_string.data;
+    size_t      srclen = pargs[0].as_string.size;
+
+    if (srclen == 0 || !isdigit(srcstr[0]))
+        return returnValues2(error, runtime, rets, "ns", "String doesn't contain an integer");
+
+    int64_t result = 0;
+    size_t i = 0;
+    do {
+        int digit = srcstr[i] - '0';
+        if (result > (INT64_MAX - digit) / 10)
+            return returnValues2(error, runtime, rets, "ns", "An overflow occurred");
+        result = result * 10 + digit;
+        i++;
+    } while (i < srclen && isdigit(srcstr[i]));
+
+    if (i < srclen)
+        // Found something other than a digit after the
+        // sequence of digits, therefore the string can't
+        // be considered an integer.
+        return returnValues2(error, runtime, rets, "ns", "String doesn't contain an integer");
+    
+    return returnValues2(error, runtime, rets, "i", result);
+}
+
 StaticMapSlot bins_string[] = {
-    { "ord", SM_FUNCT, .as_funct = bin_ord, .argc = 1 },
-    { "chr", SM_FUNCT, .as_funct = bin_chr, .argc = 1 },
-    { "cat", SM_FUNCT, .as_funct = bin_cat, .argc = -1 },
+    { "ord",  SM_FUNCT, .as_funct = bin_ord, .argc = 1 },
+    { "chr",  SM_FUNCT, .as_funct = bin_chr, .argc = 1 },
+    { "cat",  SM_FUNCT, .as_funct = bin_cat, .argc = -1 },
+    { "trim", SM_FUNCT, .as_funct = bin_trim, .argc = 1 },
+    { "slice", SM_FUNCT, .as_funct = bin_slice, .argc = 3 },
+    { "toInt", SM_FUNCT, .as_funct = bin_toInt, .argc = 1 },
 };