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author | Hans Boehm <hboehm@google.com> | 2015-10-11 15:50:03 +0000 |
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committer | Android Git Automerger <android-git-automerger@android.com> | 2015-10-11 15:50:03 +0000 |
commit | 6c26db27399f73f90a15b3a1af9ff0b43d553ffd (patch) | |
tree | 17139026360b5a053e09c40a4481383cc0925169 | |
parent | 73868209c19e2cf84b198c6224c6953a758c0b61 (diff) | |
parent | 68db0665c1e0e608c23f8a35bf97b4d39305827f (diff) | |
download | android_packages_apps_ExactCalculator-6c26db27399f73f90a15b3a1af9ff0b43d553ffd.tar.gz android_packages_apps_ExactCalculator-6c26db27399f73f90a15b3a1af9ff0b43d553ffd.tar.bz2 android_packages_apps_ExactCalculator-6c26db27399f73f90a15b3a1af9ff0b43d553ffd.zip |
am 68db0665: Merge "Generalize % operator: Handle 100+10% as expected" into mnc-dr-dev
* commit '68db0665c1e0e608c23f8a35bf97b4d39305827f':
Generalize % operator: Handle 100+10% as expected
-rw-r--r-- | src/com/android/calculator2/CalculatorExpr.java | 80 |
1 files changed, 71 insertions, 9 deletions
diff --git a/src/com/android/calculator2/CalculatorExpr.java b/src/com/android/calculator2/CalculatorExpr.java index 77e53ea..14d9236 100644 --- a/src/com/android/calculator2/CalculatorExpr.java +++ b/src/com/android/calculator2/CalculatorExpr.java @@ -317,7 +317,7 @@ class CalculatorExpr { } // In writing out PreEvals, we are careful to avoid writing // out duplicates. We assume that two expressions are - // duplicates if they have the same mVal. This avoids a + // duplicates if they have the same CR value. This avoids a // potential exponential blow up in certain off cases and // redundant evaluation after reading them back in. // The parameter hash map maps expressions we've seen @@ -1029,6 +1029,58 @@ class CalculatorExpr { return new EvalRet(cpos, crVal, ratVal); } + /** + * Is the subexpression starting at pos a simple percent constant? + * This is used to recognize exppressions like 200+10%, which we handle specially. + * This is defined as a Constant or PreEval token, followed by a percent sign, and followed + * by either nothing or an additive operator. + * Note that we are intentionally far more restrictive in recognizing such expressions than + * e.g. http://blogs.msdn.com/b/oldnewthing/archive/2008/01/10/7047497.aspx . + * When in doubt, we fall back to the the naive interpretation of % as 1/100. + * Note that 100+(10)% yields 100.1 while 100+10% yields 110. This may be controversial, + * but is consistent with Google web search. + */ + private boolean isPercent(int pos) { + if (mExpr.size() < pos + 2 || !isOperatorUnchecked(pos + 1, R.id.op_pct)) { + return false; + } + Token number = mExpr.get(pos); + if (number instanceof Operator) { + return false; + } + if (mExpr.size() == pos + 2) { + return true; + } + if (!(mExpr.get(pos + 2) instanceof Operator)) { + return false; + } + Operator op = (Operator) mExpr.get(pos + 2); + return op.id == R.id.op_add || op.id == R.id.op_sub; + } + + /** + * Compute the multiplicative factor corresponding to an N% addition or subtraction. + * @param pos position of Constant or PreEval expression token corresponding to N + * @param isSubtraction this is a subtraction, as opposed to addition + * @param ec usable evaluation contex; only length matters + * @return Rational and CR values; position is pos + 2, i.e. after percent sign + */ + private EvalRet getPercentFactor(int pos, boolean isSubtraction, EvalContext ec) + throws SyntaxException { + EvalRet tmp = evalUnary(pos, ec); + BoundedRational ratVal = isSubtraction ? BoundedRational.negate(tmp.ratVal) + : tmp.ratVal; + CR crVal = isSubtraction ? tmp.val.negate() : tmp.val; + ratVal = BoundedRational.add(BoundedRational.ONE, + BoundedRational.multiply(ratVal, RATIONAL_ONE_HUNDREDTH)); + if (ratVal == null) { + crVal = CR.ONE.add(crVal.multiply(REAL_ONE_HUNDREDTH)); + } else { + crVal = ratVal.CRValue(); + } + return new EvalRet(pos + 2 /* after percent sign */, crVal, ratVal); + } + private EvalRet evalExpr(int i, EvalContext ec) throws SyntaxException { EvalRet tmp = evalTerm(i, ec); boolean is_plus; @@ -1037,20 +1089,30 @@ class CalculatorExpr { BoundedRational ratVal = tmp.ratVal; while ((is_plus = isOperator(cpos, R.id.op_add, ec)) || isOperator(cpos, R.id.op_sub, ec)) { - tmp = evalTerm(cpos+1, ec); - if (is_plus) { - ratVal = BoundedRational.add(ratVal, tmp.ratVal); + if (isPercent(cpos + 1)) { + tmp = getPercentFactor(cpos + 1, !is_plus, ec); + ratVal = BoundedRational.multiply(ratVal, tmp.ratVal); if (ratVal == null) { - crVal = crVal.add(tmp.val); + crVal = crVal.multiply(tmp.val); } else { crVal = ratVal.CRValue(); } } else { - ratVal = BoundedRational.subtract(ratVal, tmp.ratVal); - if (ratVal == null) { - crVal = crVal.subtract(tmp.val); + tmp = evalTerm(cpos + 1, ec); + if (is_plus) { + ratVal = BoundedRational.add(ratVal, tmp.ratVal); + if (ratVal == null) { + crVal = crVal.add(tmp.val); + } else { + crVal = ratVal.CRValue(); + } } else { - crVal = ratVal.CRValue(); + ratVal = BoundedRational.subtract(ratVal, tmp.ratVal); + if (ratVal == null) { + crVal = crVal.subtract(tmp.val); + } else { + crVal = ratVal.CRValue(); + } } } cpos = tmp.pos; |