use fast parser for large bigdecimals (500+ chars) (#1157)

Author: pjfanning

src/main/java/com/fasterxml/jackson/core/io/BigDecimalParser.java

@@ -57,7 +57,7 @@ public static BigDecimal parse(final char[] chars, final int off, final int len)
             if (len < 500) {
                 return new BigDecimal(chars, off, len);
             }
-            return parseBigDecimal(chars, off, len, len / 10);
+            return JavaBigDecimalParser.parseBigDecimal(chars, off, len);
 
         // 20-Aug-2022, tatu: Although "new BigDecimal(...)" only throws NumberFormatException
         //    operations by "parseBigDecimal()" can throw "ArithmeticException", so handle both:
@@ -111,132 +111,4 @@ public static BigDecimal parseWithFastParser(final char[] ch, final int off, fin
                     + "\" can not be represented as `java.math.BigDecimal`, reason: " + nfe.getMessage());
         }
     }
-
-    private static BigDecimal parseBigDecimal(final char[] chars, final int off, final int len, final int splitLen) {
-        boolean numHasSign = false;
-        boolean expHasSign = false;
-        boolean neg = false;
-        int numIdx = off;
-        int expIdx = -1;
-        int dotIdx = -1;
-        int scale = 0;
-        final int endIdx = off + len;
-
-        for (int i = off; i < endIdx; i++) {
-            char c = chars[i];
-            switch (c) {
-            case '+':
-                if (expIdx >= 0) {
-                    if (expHasSign) {
-                        throw new NumberFormatException("Multiple signs in exponent");
-                    }
-                    expHasSign = true;
-                } else {
-                    if (numHasSign) {
-                        throw new NumberFormatException("Multiple signs in number");
-                    }
-                    numHasSign = true;
-                    numIdx = i + 1;
-                }
-                break;
-            case '-':
-                if (expIdx >= 0) {
-                    if (expHasSign) {
-                        throw new NumberFormatException("Multiple signs in exponent");
-                    }
-                    expHasSign = true;
-                } else {
-                    if (numHasSign) {
-                        throw new NumberFormatException("Multiple signs in number");
-                    }
-                    numHasSign = true;
-                    neg = true;
-                    numIdx = i + 1;
-                }
-                break;
-            case 'e':
-            case 'E':
-                if (expIdx >= 0) {
-                    throw new NumberFormatException("Multiple exponent markers");
-                }
-                expIdx = i;
-                break;
-            case '.':
-                if (dotIdx >= 0) {
-                    throw new NumberFormatException("Multiple decimal points");
-                }
-                dotIdx = i;
-                break;
-            default:
-                if (dotIdx >= 0 && expIdx == -1) {
-                    scale++;
-                }
-            }
-        }
-
-        int numEndIdx;
-        int exp = 0;
-        if (expIdx >= 0) {
-            numEndIdx = expIdx;
-            String expStr = new String(chars, expIdx + 1, endIdx - expIdx - 1);
-            exp = Integer.parseInt(expStr);
-            scale = adjustScale(scale, exp);
-        } else {
-            numEndIdx = endIdx;
-        }
-
-        BigDecimal res;
-
-        if (dotIdx >= 0) {
-            int leftLen = dotIdx - numIdx;
-            BigDecimal left = toBigDecimalRec(chars, numIdx, leftLen, exp, splitLen);
-
-            int rightLen = numEndIdx - dotIdx - 1;
-            BigDecimal right = toBigDecimalRec(chars, dotIdx + 1, rightLen, exp - rightLen, splitLen);
-
-            res = left.add(right);
-        } else {
-            res = toBigDecimalRec(chars, numIdx, numEndIdx - numIdx, exp, splitLen);
-        }
-
-        if (scale != 0) {
-            res = res.setScale(scale);
-        }
-
-        if (neg) {
-            res = res.negate();
-        }
-
-        return res;
-    }
-
-    private static int adjustScale(int scale, long exp) {
-        long adjScale = scale - exp;
-        if (adjScale > Integer.MAX_VALUE || adjScale < Integer.MIN_VALUE) {
-            throw new NumberFormatException(
-                    "Scale out of range: " + adjScale + " while adjusting scale " + scale + " to exponent " + exp);
-        }
-
-        return (int) adjScale;
-    }
-
-    private static BigDecimal toBigDecimalRec(final char[] chars, final int off, final int len,
-                                              final int scale, final int splitLen) {
-        if (len > splitLen) {
-            int mid = len / 2;
-            BigDecimal left = toBigDecimalRec(chars, off, mid, scale + len - mid, splitLen);
-            BigDecimal right = toBigDecimalRec(chars, off + mid, len - mid, scale, splitLen);
-
-            return left.add(right);
-        }
-
-        if (len == 0) {
-            return BigDecimal.ZERO;
-        }
-        // 02-Apr-2023, tatu: [core#967] Looks like "scaleByPowerOfThen" avoids performance issue
-        //    there would be with "movePointRight" (both doing about same thing), so)
-        return new BigDecimal(chars, off, len)
-//                .movePointRight(scale);
-                .scaleByPowerOfTen(scale);
-    }
 }