Complex classes like DecimalMath often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use DecimalMath, and based on these observations, apply Extract Interface, too.
1 | <?php |
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24 | class DecimalMath { |
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25 | |||
26 | /** |
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27 | * Whether to use the bcmath library. |
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28 | * |
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29 | * @var bool |
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30 | */ |
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31 | private $useBC; |
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32 | |||
33 | /** |
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34 | * @param bool|null $useBC Whether to use the bcmath library. If null, |
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35 | * bcmath will automatically be used if available. |
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36 | */ |
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37 | 224 | public function __construct( $useBC = null ) { |
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44 | |||
45 | /** |
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46 | * Whether this is using the bcmath library. |
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47 | * |
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48 | * @return bool |
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49 | */ |
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50 | public function getUseBC() { |
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53 | |||
54 | /** |
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55 | * @param DecimalValue $a |
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56 | * @param DecimalValue $b |
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57 | * |
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58 | * @return DecimalValue |
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59 | */ |
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60 | 28 | public function product( DecimalValue $a, DecimalValue $b ) { |
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66 | |||
67 | /** |
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68 | * @param DecimalValue $a |
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69 | * @param DecimalValue $b |
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70 | * |
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71 | * @return DecimalValue |
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72 | */ |
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73 | 16 | private function productWithBC( DecimalValue $a, DecimalValue $b ) { |
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85 | |||
86 | /** |
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87 | * @param DecimalValue $a |
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88 | * @param DecimalValue $b |
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89 | * |
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90 | * @return DecimalValue |
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91 | */ |
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92 | 12 | private function productWithoutBC( DecimalValue $a, DecimalValue $b ) { |
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106 | |||
107 | /** |
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108 | * @param DecimalValue $a |
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109 | * @param DecimalValue $b |
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110 | * |
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111 | * @return DecimalValue |
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112 | */ |
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113 | 9 | public function sum( DecimalValue $a, DecimalValue $b ) { |
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123 | |||
124 | /** |
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125 | * @param DecimalValue $a |
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126 | * @param DecimalValue $b |
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127 | * |
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128 | * @return DecimalValue |
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129 | */ |
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130 | 5 | public function min( DecimalValue $a, DecimalValue $b ) { |
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142 | |||
143 | /** |
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144 | * @param DecimalValue $a |
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145 | * @param DecimalValue $b |
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146 | * |
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147 | * @return DecimalValue |
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148 | */ |
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149 | 5 | public function max( DecimalValue $a, DecimalValue $b ) { |
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161 | |||
162 | /** |
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163 | * Returns the given value, with any insignificant digits removed or zeroed. |
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164 | * |
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165 | * Rounding is applied using the "round half away from zero" rule (that is, +0.5 is |
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166 | * rounded to +1 and -0.5 is rounded to -1). |
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167 | * |
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168 | * @since 0.1 |
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169 | * |
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170 | * @param DecimalValue $decimal |
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171 | * @param int $significantDigits The number of digits to retain, counting the decimal point, |
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172 | * but not counting the leading sign. |
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173 | * |
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174 | * @throws InvalidArgumentException |
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175 | * @return DecimalValue |
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176 | */ |
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177 | 105 | public function roundToDigit( DecimalValue $decimal, $significantDigits ) { |
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182 | |||
183 | /** |
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184 | * Returns the given value, with any insignificant digits removed or zeroed. |
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185 | * |
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186 | * Rounding is applied using the "round half away from zero" rule (that is, +0.5 is |
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187 | * rounded to +1 and -0.5 is rounded to -1). |
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188 | * |
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189 | * @since 0.1 |
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190 | * |
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191 | * @param DecimalValue $decimal |
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192 | * @param int $significantExponent The exponent of the last significant digit, |
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193 | * e.g. -1 for "keep the first digit after the decimal point", or 2 for |
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194 | * "zero the last two digits before the decimal point". |
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195 | * |
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196 | * @throws InvalidArgumentException |
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197 | * @return DecimalValue |
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198 | */ |
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199 | 47 | public function roundToExponent( DecimalValue $decimal, $significantExponent ) { |
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205 | |||
206 | /** |
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207 | * Returns the (zero based) position for the given exponent in |
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208 | * the given decimal string, counting the decimal point and the leading sign. |
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209 | * |
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210 | * @example: the position of exponent 0 in "+10.03" is 2. |
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211 | * @example: the position of exponent 1 in "+210.03" is 2. |
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212 | * @example: the position of exponent -2 in "+1.037" is 4. |
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213 | * |
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214 | * @param int $exponent |
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215 | * @param DecimalValue $decimal |
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216 | * |
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217 | * @return int |
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218 | */ |
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219 | 53 | public function getPositionForExponent( $exponent, DecimalValue $decimal ) { |
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240 | |||
241 | /** |
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242 | * Returns the given value, with any insignificant digits removed or zeroed. |
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243 | * |
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244 | * Rounding is applied using the "round half away from zero" rule (that is, +0.5 is |
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245 | * rounded to +1 and -0.5 is rounded to -1). |
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246 | * |
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247 | * @see round() |
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248 | * |
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249 | * @param string $value |
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250 | * @param int $significantDigits |
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251 | * |
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252 | * @throws InvalidArgumentException if $significantDigits is smaller than 0 |
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253 | * @return string |
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254 | */ |
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255 | 121 | private function roundDigits( $value, $significantDigits ) { |
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318 | |||
319 | /** |
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320 | * Increment the least significant digit by one if it is less than 9, and |
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321 | * set it to zero and continue to the next more significant digit if it is 9. |
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322 | * Exception: bump( 0 ) == 1; |
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323 | * |
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324 | * E.g.: bump( 0.2 ) == 0.3, bump( -0.09 ) == -0.10, bump( 9.99 ) == 10.00 |
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325 | * |
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326 | * This is the inverse of @see slump() |
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327 | * |
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328 | * @since 0.1 |
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329 | * |
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330 | * @param DecimalValue $decimal |
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331 | * |
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332 | * @return DecimalValue |
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333 | */ |
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334 | 16 | public function bump( DecimalValue $decimal ) { |
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339 | |||
340 | /** |
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341 | * Increment the least significant digit by one if it is less than 9, and |
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342 | * set it to zero and continue to the next more significant digit if it is 9. |
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343 | * |
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344 | * @see bump() |
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345 | * |
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346 | * @param string $value |
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347 | * @return string |
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348 | */ |
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349 | 43 | private function bumpDigits( $value ) { |
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377 | |||
378 | /** |
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379 | * Decrement the least significant digit by one if it is more than 0, and |
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380 | * set it to 9 and continue to the next more significant digit if it is 0. |
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381 | * Exception: slump( 0 ) == -1; |
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382 | * |
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383 | * E.g.: slump( 0.2 ) == 0.1, slump( -0.10 ) == -0.01, slump( 0.0 ) == -1.0 |
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384 | * |
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385 | * This is the inverse of @see bump() |
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386 | * |
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387 | * @since 0.1 |
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388 | * |
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389 | * @param DecimalValue $decimal |
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390 | * |
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391 | * @return DecimalValue |
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392 | */ |
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393 | 24 | public function slump( DecimalValue $decimal ) { |
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398 | |||
399 | /** |
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400 | * Decrement the least significant digit by one if it is more than 0, and |
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401 | * set it to 9 and continue to the next more significant digit if it is 0. |
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402 | * |
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403 | * @see slump() |
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404 | * |
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405 | * @param string $value |
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406 | * @return string |
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407 | */ |
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408 | 24 | private function slumpDigits( $value ) { |
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448 | |||
449 | /** |
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450 | * @param string $digits |
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451 | * |
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452 | * @return string |
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453 | */ |
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454 | 40 | private function stripLeadingZeros( $digits ) { |
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458 | |||
459 | /** |
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460 | * Shift the decimal point according to the given exponent. |
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461 | * |
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462 | * @param DecimalValue $decimal |
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463 | * @param int $exponent The exponent to apply (digits to shift by). A Positive exponent |
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464 | * shifts the decimal point to the right, a negative exponent shifts to the left. |
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465 | * |
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466 | * @throws InvalidArgumentException |
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467 | * @return DecimalValue |
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468 | */ |
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469 | 26 | public function shift( DecimalValue $decimal, $exponent ) { |
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493 | |||
494 | /** |
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495 | * @param string $intPart |
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496 | * @param int $exponent must be negative |
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497 | * |
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498 | * @return string |
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499 | */ |
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500 | 14 | private function shiftLeft( $intPart, $exponent ) { |
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510 | |||
511 | /** |
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512 | * @param string $fractPart |
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513 | * @param int $exponent must be positive |
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514 | * |
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515 | * @return string |
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516 | */ |
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517 | 8 | private function shiftRight( $fractPart, $exponent ) { |
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527 | |||
528 | } |
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529 |