1 files changed, 171 insertions, 0 deletions
diff --git a/subex/filter.go b/subex/filter.go
index 309d6c7..87c83a4 100644
--- a/subex/filter.go
+++ b/subex/filter.go
@@ -2,6 +2,8 @@ package subex
 
 import (
 	"main/walk"
+	"math"
+	"fmt"
 )
 
 type valueFilter interface {
@@ -86,3 +88,172 @@ type selectRuneFilter struct {
 func (f selectRuneFilter) runeFilter(r rune) bool {
 	return f.r == r
 }
+
+type numberFilter interface {
+	add(m float64) numberFilter
+	multiply(m float64) numberFilter
+	numberFilter(n float64) bool
+}
+
+func (_ anyNumberFilter) numberFilter(n float64) bool {
+	return true
+}
+func (_ anyNumberFilter) add(m float64) numberFilter {
+	return anyNumberFilter{}
+}
+func (_ anyNumberFilter) multiply(m float64) numberFilter {
+	if m == 0.0 {
+		return equalNumberFilter {0.0}
+	} else {
+		return anyNumberFilter{}
+	}
+}
+func (_ anyNumberFilter) String() string {
+	return "r"
+}
+
+type divisibleNumberFilter struct {
+	divisor float64
+	target float64
+}
+func (d divisibleNumberFilter) numberFilter(n float64) bool {
+	mod := math.Mod(n, d.divisor)
+	if mod < 0 {
+		mod += d.divisor
+	}
+	return mod == d.target
+}
+func (d divisibleNumberFilter) add(m float64) numberFilter {
+	mod := math.Mod(m + d.target, d.divisor)
+	if mod < 0 {
+		mod += d.divisor
+	}
+	return divisibleNumberFilter {
+		divisor: d.divisor,
+		target: mod,
+	}
+}
+func (d divisibleNumberFilter) multiply(m float64) numberFilter {
+	if m == 0.0 {
+		return equalNumberFilter {0.0}
+	}
+
+	target := d.target
+	if m < 0 {
+		target = d.divisor - target
+		m = -m
+	}
+
+	return divisibleNumberFilter {
+		divisor: d.divisor * m,
+		target: target * m,
+	}
+}
+func (d divisibleNumberFilter) String() string {
+	return fmt.Sprintf("(x %% %v == %v)", d.divisor, d.target)
+}
+
+type andNumberFilter struct {
+	lhs, rhs numberFilter
+}
+func (a andNumberFilter) numberFilter(n float64) bool {
+	return a.lhs.numberFilter(n) && a.rhs.numberFilter(n)
+}
+func (a andNumberFilter) add(m float64) numberFilter {
+	return andNumberFilter {
+		lhs: a.lhs.add(m),
+		rhs: a.rhs.add(m),
+	}
+}
+func (a andNumberFilter) multiply(m float64) numberFilter {
+	return andNumberFilter {
+		lhs: a.lhs.multiply(m),
+		rhs: a.rhs.multiply(m),
+	}
+}
+func (a andNumberFilter) String() string {
+	return fmt.Sprintf("(%v && %v)", a.lhs, a.rhs)
+}
+
+type orNumberFilter struct {
+	lhs, rhs numberFilter
+}
+func (o orNumberFilter) numberFilter(n float64) bool {
+	return o.lhs.numberFilter(n) || o.rhs.numberFilter(n)
+}
+func (o orNumberFilter) String() string {
+	return fmt.Sprintf("(%v || %v)", o.lhs, o.rhs)
+}
+
+type notNumberFilter struct {
+	operand numberFilter
+}
+func (no notNumberFilter) numberFilter(n float64) bool {
+	return !no.operand.numberFilter(n)
+}
+func (no notNumberFilter) add(m float64) numberFilter {
+	return notNumberFilter {no.operand.add(m)}
+}
+func (no notNumberFilter) multiply(m float64) numberFilter {
+	return notNumberFilter {no.operand.multiply(m)}
+}
+func (no notNumberFilter) String() string {
+	return fmt.Sprintf("(!%v)", no.operand)
+}
+
+type lessThanNumberFilter struct {
+	rhs float64
+}
+func (l lessThanNumberFilter) numberFilter(n float64) bool {
+	return n < l.rhs
+}
+func (l lessThanNumberFilter) add(m float64) numberFilter {
+	return lessThanNumberFilter {l.rhs + m}
+}
+func (l lessThanNumberFilter) multiply(m float64) numberFilter {
+	if m > 0 {
+		return lessThanNumberFilter {l.rhs * m}
+	} else if m < 0 {
+		return greaterThanNumberFilter {l.rhs * m}
+	} else {
+		return equalNumberFilter {0}
+	}
+}
+func (l lessThanNumberFilter) String() string {
+	return fmt.Sprintf("(x < %v)", l.rhs)
+}
+
+type greaterThanNumberFilter struct {
+	rhs float64
+}
+func (g greaterThanNumberFilter) numberFilter(n float64) bool {
+	return n > g.rhs
+}
+func (g greaterThanNumberFilter) add(m float64) numberFilter {
+	return greaterThanNumberFilter {g.rhs + m}
+}
+func (g greaterThanNumberFilter) multiply(m float64) numberFilter {
+	if m > 0 {
+		return greaterThanNumberFilter {g.rhs * m}
+	} else if m < 0 {
+		return lessThanNumberFilter {g.rhs * m}
+	} else {
+		return equalNumberFilter {0}
+	}
+}
+func (g greaterThanNumberFilter) String() string {
+	return fmt.Sprintf("(x > %v)", g.rhs)
+}
+
+type equalNumberFilter struct {
+	rhs float64
+}
+func (e equalNumberFilter) numberFilter(n float64) bool {
+	return n == e.rhs
+}
+func (e equalNumberFilter) add(m float64) numberFilter {
+	return equalNumberFilter {e.rhs + m}
+}
+func (e equalNumberFilter) multiply(m float64) numberFilter {
+	return equalNumberFilter {e.rhs * m}
+}