sorted set

src/datastruct/sortedset/border.go

@@ -0,0 +1,89 @@
+package sortedset
+
+import (
+    "errors"
+    "strconv"
+)
+
+/*
+ * ScoreBorder is a struct represents `min` `max` parameter of redis command `ZRANGEBYSCORE`
+ * can accept:
+ *   int or float value, such as 2.718, 2, -2.718, -2 ...
+ *   exclusive int or float value, such as (2.718, (2, (-2.718, (-2 ...
+ *   infinity: +inf, -inf， inf(same as +inf)
+ */
+
+const (
+    negativeInf int8 = -1
+    positiveInf int8 = 1
+)
+
+type ScoreBorder struct {
+    Inf int8
+    Value float64
+    Exclude bool
+}
+
+func (border *ScoreBorder)greater(value float64)bool {
+    if border.Inf == negativeInf {
+        return false
+    } else if border.Inf == positiveInf {
+        return true
+    }
+    if border.Exclude {
+        return border.Value > value
+    } else {
+        return border.Value >= value
+    }
+}
+
+func (border *ScoreBorder)less(value float64)bool {
+    if border.Inf == negativeInf {
+        return true
+    } else if border.Inf == positiveInf {
+        return false
+    }
+    if border.Exclude {
+        return border.Value < value
+    } else {
+        return border.Value <= value
+    }
+}
+
+var positiveInfBorder = &ScoreBorder {
+    Inf: positiveInf,
+}
+
+var negativeInfBorder = &ScoreBorder {
+    Inf: negativeInf,
+}
+
+func ParseScoreBorder(s string)(*ScoreBorder, error) {
+    if s == "inf" || s == "+inf" {
+        return positiveInfBorder, nil
+    }
+    if s == "-inf" {
+        return negativeInfBorder, nil
+    }
+    if s[0] == '(' {
+        value, err := strconv.ParseFloat(s[1:], 64)
+        if err != nil {
+            return nil, errors.New("ERR min or max is not a float")
+        }
+        return &ScoreBorder{
+            Inf: 0,
+            Value: value,
+            Exclude: true,
+        }, nil
+    } else {
+        value, err := strconv.ParseFloat(s, 64)
+        if err != nil {
+            return nil, errors.New("ERR min or max is not a float")
+        }
+        return &ScoreBorder{
+            Inf: 0,
+            Value: value,
+            Exclude: false,
+        }, nil
+    }
+}