Broken site based impl

lib/rt/number.h

@@ -0,0 +1,93 @@
+// The number natives: conversions between numbers and strings
+#pragma once
+
+#include "str.h"
+
+#ifdef JSRT_IMPLEMENTATION
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// JS's Number::toString: the fewest digits that give the number back. Plain
+// notation while the decimal point is within 21 places, else exponential
+string_t __native_number_to_string(double x) {
+    if (isnan(x)) return jsrt_string_lit("NaN");
+    if (isinf(x)) return jsrt_string_lit(x < 0 ? "-Infinity" : "Infinity");
+    if (x == 0) return jsrt_string_lit("0");
+
+    // The fewest digits: buf is [-]d[.ddd]e±xx
+    char buf[64];
+
+    for (int precision = 0; precision < 17; precision++) {
+        snprintf(buf, sizeof buf, "%.*e", precision, x);
+
+        if (strtod(buf, NULL) == x) {
+            break;
+        }
+    }
+
+    char digits[32], out[64];
+    char *p = buf, *o = out;
+    int n = 0;
+
+    if (*p == '-') {
+        *o++ = *p++;
+    }
+
+    for (; *p != 'e'; p++) {
+        if (*p != '.') {
+            digits[n++] = *p;
+        }
+    }
+
+    digits[n] = 0;
+
+    // The decimal point goes after the first `point` digits
+    int point = atoi(p + 1) + 1;
+
+    if (n <= point && point <= 21) {
+        o += sprintf(o, "%s", digits);
+        for (int i = n; i < point; i++) *o++ = '0';
+        *o = 0;
+    } else if (0 < point && point <= 21) {
+        sprintf(o, "%.*s.%s", point, digits, digits + point);
+    } else if (-6 < point && point <= 0) {
+        o += sprintf(o, "0.");
+        for (int i = point; i < 0; i++) *o++ = '0';
+        sprintf(o, "%s", digits);
+    } else {
+        int e = point - 1;
+        sprintf(o, "%c%s%se%c%d", digits[0], n > 1 ? "." : "", digits + 1, e < 0 ? '-' : '+', abs(e));
+    }
+
+    return jsrt_string_lit(out);
+}
+
+string_t __native_number_to_fixed(double x, int32_t digits) {
+    char buf[400];
+    snprintf(buf, sizeof buf, "%.*f", digits, x);
+    return jsrt_string_lit(buf);
+}
+
+// JS's ToNumber on a string: a decimal number with whitespace around it, or
+// only whitespace, which is 0. Anything else is NaN
+double __native_string_to_number(string_t s) {
+    char *utf8 = jsrt_string_utf8(s);
+    char *start = utf8, *end;
+
+    while (*start == ' ' || (*start >= '\t' && *start <= '\r')) start++;
+
+    double x = 0;
+
+    if (*start) {
+        x = strtod(start, &end);
+        while (*end == ' ' || (*end >= '\t' && *end <= '\r')) end++;
+        if (*end || start == end) x = NAN;
+    }
+
+    free(utf8);
+    return x;
+}
+
+#endif // JSRT_IMPLEMENTATION