From 4e5e2ed9487b5591a148c917ff79cc4c6fb56a14 Mon Sep 17 00:00:00 2001
From: Jason Biegel <jason.biegel@shopspring.com>
Date: Tue, 7 Feb 2017 12:33:26 -0500
Subject: [PATCH] Remove insignificant digits during string parsing

---
 decimal.go      |  6 ++++--
 decimal_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/decimal.go b/decimal.go
index 3942b3d..045badb 100644
--- a/decimal.go
+++ b/decimal.go
@@ -112,8 +112,10 @@ func NewFromString(value string) (Decimal, error) {
 		// an int
 		intString = value
 	} else if len(parts) == 2 {
-		intString = parts[0] + parts[1]
-		expInt := -len(parts[1])
+		// strip the insignificant digits for more accurate comparisons.
+		decimalPart := strings.TrimRight(parts[1], "0")
+		intString = parts[0] + decimalPart
+		expInt := -len(decimalPart)
 		exp += int64(expInt)
 	} else {
 		return Decimal{}, fmt.Errorf("can't convert %s to decimal: too many .s", value)
diff --git a/decimal_test.go b/decimal_test.go
index 718943a..60dc6fa 100644
--- a/decimal_test.go
+++ b/decimal_test.go
@@ -5,6 +5,7 @@ import (
 	"encoding/xml"
 	"math"
 	"math/big"
+	"reflect"
 	"sort"
 	"strconv"
 	"strings"
@@ -156,6 +157,34 @@ func TestNewFromStringErrs(t *testing.T) {
 	}
 }
 
+func TestNewFromStringDeepEquals(t *testing.T) {
+	type StrCmp struct {
+		str1     string
+		str2     string
+		expected bool
+	}
+	tests := []StrCmp{
+		StrCmp{"1", "1", true},
+		StrCmp{"10", "10.0", true},
+		StrCmp{"1.1", "1.10", true},
+		StrCmp{"1.001", "1.01", false},
+	}
+
+	for _, cmp := range tests {
+		d1, err1 := NewFromString(cmp.str1)
+		d2, err2 := NewFromString(cmp.str2)
+
+		if err1 != nil || err2 != nil {
+			t.Errorf("error parsing strings to decimals")
+		}
+
+		if reflect.DeepEqual(d1, d2) != cmp.expected {
+			t.Errorf("comparison result is different from expected results for %s and %s",
+				cmp.str1, cmp.str2)
+		}
+	}
+}
+
 func TestNewFromFloatWithExponent(t *testing.T) {
 	type Inp struct {
 		float float64