1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #ifndef V8_CONVERSIONS_H_
6 #define V8_CONVERSIONS_H_
7
8 #include <limits>
9
10 #include "src/checks.h"
11 #include "src/handles.h"
12 #include "src/objects.h"
13 #include "src/utils.h"
14
15 namespace v8 {
16 namespace internal {
17
18 class UnicodeCache;
19
20 // Maximum number of significant digits in decimal representation.
21 // The longest possible double in decimal representation is
22 // (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
23 // (768 digits). If we parse a number whose first digits are equal to a
24 // mean of 2 adjacent doubles (that could have up to 769 digits) the result
25 // must be rounded to the bigger one unless the tail consists of zeros, so
26 // we don't need to preserve all the digits.
27 const int kMaxSignificantDigits = 772;
28
29
isDigit(int x,int radix)30 inline bool isDigit(int x, int radix) {
31 return (x >= '0' && x <= '9' && x < '0' + radix)
32 || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
33 || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
34 }
35
36
isBinaryDigit(int x)37 inline bool isBinaryDigit(int x) {
38 return x == '0' || x == '1';
39 }
40
41
42 // The fast double-to-(unsigned-)int conversion routine does not guarantee
43 // rounding towards zero.
44 // For NaN and values outside the int range, return INT_MIN or INT_MAX.
FastD2IChecked(double x)45 inline int FastD2IChecked(double x) {
46 if (!(x >= INT_MIN)) return INT_MIN; // Negation to catch NaNs.
47 if (x > INT_MAX) return INT_MAX;
48 return static_cast<int>(x);
49 }
50
51
52 // The fast double-to-(unsigned-)int conversion routine does not guarantee
53 // rounding towards zero.
54 // The result is unspecified if x is infinite or NaN, or if the rounded
55 // integer value is outside the range of type int.
FastD2I(double x)56 inline int FastD2I(double x) {
57 return static_cast<int32_t>(x);
58 }
59
60 inline unsigned int FastD2UI(double x);
61
62
FastI2D(int x)63 inline double FastI2D(int x) {
64 // There is no rounding involved in converting an integer to a
65 // double, so this code should compile to a few instructions without
66 // any FPU pipeline stalls.
67 return static_cast<double>(x);
68 }
69
70
FastUI2D(unsigned x)71 inline double FastUI2D(unsigned x) {
72 // There is no rounding involved in converting an unsigned integer to a
73 // double, so this code should compile to a few instructions without
74 // any FPU pipeline stalls.
75 return static_cast<double>(x);
76 }
77
78
79 // This function should match the exact semantics of ECMA-262 9.4.
80 inline double DoubleToInteger(double x);
81
82
83 // This function should match the exact semantics of ECMA-262 9.5.
84 inline int32_t DoubleToInt32(double x);
85
86
87 // This function should match the exact semantics of ECMA-262 9.6.
DoubleToUint32(double x)88 inline uint32_t DoubleToUint32(double x) {
89 return static_cast<uint32_t>(DoubleToInt32(x));
90 }
91
92
93 // Enumeration for allowing octals and ignoring junk when converting
94 // strings to numbers.
95 enum ConversionFlags {
96 NO_FLAGS = 0,
97 ALLOW_HEX = 1,
98 ALLOW_OCTAL = 2,
99 ALLOW_IMPLICIT_OCTAL = 4,
100 ALLOW_BINARY = 8,
101 ALLOW_TRAILING_JUNK = 16
102 };
103
104
105 // Converts a string into a double value according to ECMA-262 9.3.1
106 double StringToDouble(UnicodeCache* unicode_cache,
107 Vector<const uint8_t> str,
108 int flags,
109 double empty_string_val = 0);
110 double StringToDouble(UnicodeCache* unicode_cache,
111 Vector<const uc16> str,
112 int flags,
113 double empty_string_val = 0);
114 // This version expects a zero-terminated character array.
115 double StringToDouble(UnicodeCache* unicode_cache,
116 const char* str,
117 int flags,
118 double empty_string_val = 0);
119
120 // Converts a string into an integer.
121 double StringToInt(UnicodeCache* unicode_cache,
122 Vector<const uint8_t> vector,
123 int radix);
124
125
126 double StringToInt(UnicodeCache* unicode_cache,
127 Vector<const uc16> vector,
128 int radix);
129
130 const int kDoubleToCStringMinBufferSize = 100;
131
132 // Converts a double to a string value according to ECMA-262 9.8.1.
133 // The buffer should be large enough for any floating point number.
134 // 100 characters is enough.
135 const char* DoubleToCString(double value, Vector<char> buffer);
136
137 // Convert an int to a null-terminated string. The returned string is
138 // located inside the buffer, but not necessarily at the start.
139 const char* IntToCString(int n, Vector<char> buffer);
140
141 // Additional number to string conversions for the number type.
142 // The caller is responsible for calling free on the returned pointer.
143 char* DoubleToFixedCString(double value, int f);
144 char* DoubleToExponentialCString(double value, int f);
145 char* DoubleToPrecisionCString(double value, int f);
146 char* DoubleToRadixCString(double value, int radix);
147
148
IsMinusZero(double value)149 static inline bool IsMinusZero(double value) {
150 static const DoubleRepresentation minus_zero(-0.0);
151 return DoubleRepresentation(value) == minus_zero;
152 }
153
154
155 // Integer32 is an integer that can be represented as a signed 32-bit
156 // integer. It has to be in the range [-2^31, 2^31 - 1].
157 // We also have to check for negative 0 as it is not an Integer32.
IsInt32Double(double value)158 static inline bool IsInt32Double(double value) {
159 return !IsMinusZero(value) &&
160 value >= kMinInt &&
161 value <= kMaxInt &&
162 value == FastI2D(FastD2I(value));
163 }
164
165
166 // UInteger32 is an integer that can be represented as an unsigned 32-bit
167 // integer. It has to be in the range [0, 2^32 - 1].
168 // We also have to check for negative 0 as it is not a UInteger32.
IsUint32Double(double value)169 static inline bool IsUint32Double(double value) {
170 return !IsMinusZero(value) &&
171 value >= 0 &&
172 value <= kMaxUInt32 &&
173 value == FastUI2D(FastD2UI(value));
174 }
175
176
177 // Convert from Number object to C integer.
NumberToInt32(Object * number)178 inline int32_t NumberToInt32(Object* number) {
179 if (number->IsSmi()) return Smi::cast(number)->value();
180 return DoubleToInt32(number->Number());
181 }
182
183
NumberToUint32(Object * number)184 inline uint32_t NumberToUint32(Object* number) {
185 if (number->IsSmi()) return Smi::cast(number)->value();
186 return DoubleToUint32(number->Number());
187 }
188
189
190 double StringToDouble(UnicodeCache* unicode_cache,
191 String* string,
192 int flags,
193 double empty_string_val = 0.0);
194
195
TryNumberToSize(Isolate * isolate,Object * number,size_t * result)196 inline bool TryNumberToSize(Isolate* isolate,
197 Object* number, size_t* result) {
198 SealHandleScope shs(isolate);
199 if (number->IsSmi()) {
200 int value = Smi::cast(number)->value();
201 ASSERT(static_cast<unsigned>(Smi::kMaxValue)
202 <= std::numeric_limits<size_t>::max());
203 if (value >= 0) {
204 *result = static_cast<size_t>(value);
205 return true;
206 }
207 return false;
208 } else {
209 ASSERT(number->IsHeapNumber());
210 double value = HeapNumber::cast(number)->value();
211 if (value >= 0 &&
212 value <= std::numeric_limits<size_t>::max()) {
213 *result = static_cast<size_t>(value);
214 return true;
215 } else {
216 return false;
217 }
218 }
219 }
220
221 // Converts a number into size_t.
NumberToSize(Isolate * isolate,Object * number)222 inline size_t NumberToSize(Isolate* isolate,
223 Object* number) {
224 size_t result = 0;
225 bool is_valid = TryNumberToSize(isolate, number, &result);
226 CHECK(is_valid);
227 return result;
228 }
229
230 } } // namespace v8::internal
231
232 #endif // V8_CONVERSIONS_H_
233