added with-precision patch from Christophe Grand

3 files changed, 54 insertions, 9 deletions

diff --git a/src/boot.clj b/src/boot.clj
index c9afa590..15323ab9 100644
--- a/src/boot.clj
+++ b/src/boot.clj
@@ -2284,4 +2284,20 @@ not-every? (comp not every?))
   once, but any effects on Refs will be atomic."
   [& exprs]
   `(sync nil ~@exprs))
-      
\ No newline at end of file
+
+(defmacro with-precision
+  "Sets the precision and rounding mode to be used for BigDecimal operations. 
+  Usage: (with-precision 10 (/ 1M 3)) 
+  or:    (with-precision 10 :rounding HALF_DOWN (/ 1M 3))
+  The rounding mode is one of CEILING, FLOOR, HALF_UP, HALF_DOWN, HALF_EVEN, 
+  UP, DOWN and UNNECESSARY; it defaults to HALF_UP."  
+  [precision & exprs]
+  (let [[body mc] 
+          (if (= (first exprs) :rounding)
+            [(rest (rest exprs))
+             (java.math.MathContext. precision 
+                                     (. clojure.lang.Reflector getStaticField java.math.RoundingMode (name (second exprs))))]
+            [exprs
+             (java.math.MathContext. precision)])]
+    `(binding [*math-context* ~mc]
+       ~@body)))
\ No newline at end of file
diff --git a/src/jvm/clojure/lang/Numbers.java b/src/jvm/clojure/lang/Numbers.java
index 91dcefe9..1cf95bb4 100644
--- a/src/jvm/clojure/lang/Numbers.java
+++ b/src/jvm/clojure/lang/Numbers.java
@@ -14,6 +14,7 @@ package clojure.lang;
 
 import java.math.BigInteger;
 import java.math.BigDecimal;
+import java.math.MathContext;
 
 public class Numbers{
 
@@ -628,6 +629,8 @@ final static class BigIntegerOps implements Ops{
 }
 
 final static class BigDecimalOps implements Ops{
+	final static Var MATH_CONTEXT = RT.MATH_CONTEXT;
+	
 	public Ops combine(Ops y){
 		return y.opsWith(this);
 	}
@@ -655,23 +658,38 @@ final static class BigDecimalOps implements Ops{
 	}
 
 	final public Number add(Number x, Number y){
-		return toBigDecimal(x).add(toBigDecimal(y));
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? toBigDecimal(x).add(toBigDecimal(y)) 
+			: toBigDecimal(x).add(toBigDecimal(y), mc);
 	}
 
 	final public Number multiply(Number x, Number y){
-		return toBigDecimal(x).multiply(toBigDecimal(y));
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? toBigDecimal(x).multiply(toBigDecimal(y)) 
+			: toBigDecimal(x).multiply(toBigDecimal(y), mc);
 	}
 
 	public Number divide(Number x, Number y){
-		return toBigDecimal(x).divide(toBigDecimal(y));
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? toBigDecimal(x).divide(toBigDecimal(y)) 
+			: toBigDecimal(x).divide(toBigDecimal(y), mc);
 	}
 
 	public Number quotient(Number x, Number y){
-		return toBigDecimal(x).divideToIntegralValue(toBigDecimal(y));
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? toBigDecimal(x).divideToIntegralValue(toBigDecimal(y)) 
+			: toBigDecimal(x).divideToIntegralValue(toBigDecimal(y), mc);
 	}
 
 	public Number remainder(Number x, Number y){
-		return toBigDecimal(x).remainder(toBigDecimal(y));
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? toBigDecimal(x).remainder(toBigDecimal(y)) 
+			: toBigDecimal(x).remainder(toBigDecimal(y), mc);
 	}
 
 	public boolean equiv(Number x, Number y){
@@ -684,17 +702,26 @@ final static class BigDecimalOps implements Ops{
 
 	//public Number subtract(Number x, Number y);
 	final public Number negate(Number x){
-		return ((BigDecimal)x).negate();
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
+		return mc == null 
+			? ((BigDecimal)x).negate() 
+			: ((BigDecimal)x).negate(mc);
 	}
 
 	public Number inc(Number x){
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
 		BigDecimal bx = (BigDecimal) x;
-		return bx.add(BigDecimal.ONE);
+		return mc == null 
+			? bx.add(BigDecimal.ONE) 
+			: bx.add(BigDecimal.ONE, mc);
 	}
 
 	public Number dec(Number x){
+		MathContext mc = (MathContext) MATH_CONTEXT.get();
 		BigDecimal bx = (BigDecimal) x;
-		return bx.subtract(BigDecimal.ONE);
+		return mc == null 
+			? bx.subtract(BigDecimal.ONE) 
+			: bx.subtract(BigDecimal.ONE, mc);
 	}
 }
 
diff --git a/src/jvm/clojure/lang/RT.java b/src/jvm/clojure/lang/RT.java
index ed4de6b7..461763ee 100644
--- a/src/jvm/clojure/lang/RT.java
+++ b/src/jvm/clojure/lang/RT.java
@@ -115,6 +115,7 @@ final static public Var IN =
 final static Keyword TAG_KEY = Keyword.intern(null, "tag");
 final static public Var AGENT = Var.intern(CLOJURE_NS, Symbol.create("*agent*"), null);
 final static public Var MACRO_META = Var.intern(CLOJURE_NS, Symbol.create("*macro-meta*"), null);
+final static public Var MATH_CONTEXT = Var.intern(CLOJURE_NS, Symbol.create("*math-context*"), null);
 static Keyword LINE_KEY = Keyword.intern(null, "line");
 static Keyword FILE_KEY = Keyword.intern(null, "file");
 //final static public Var CURRENT_MODULE = Var.intern(Symbol.create("clojure", "current-module"),
@@ -198,6 +199,7 @@ static
 	Symbol namesym = Symbol.create("name");
 	OUT.setTag(Symbol.create("java.io.Writer"));
 	CURRENT_NS.setTag(Symbol.create("clojure.lang.Namespace"));
+	MATH_CONTEXT.setTag(Symbol.create("java.math.MathContext"));
 	Var v;
 	v = Var.intern(CLOJURE_NS, IN_NAMESPACE, inNamespace);
 	v.setMeta(map(dockw, "Sets *ns* to the namespace named by the symbol, creating it if needed.",