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60 lines
1.3 KiB
Go
60 lines
1.3 KiB
Go
package ent
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import (
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"fmt"
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"github.com/jordanorelli/hyperstone/bit"
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)
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// a fieldpath is a list of integers that is used to walk the type hierarchy to
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// identify a given field on a given type.
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type fieldPath struct {
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// slice of values, to be reused over and over
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vals []int
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// index of the last valid value. e.g., the head of the stack.
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last int
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}
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func newFieldPath() *fieldPath {
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f := &fieldPath{vals: make([]int, 32)}
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f.vals[f.last] = -1
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return f
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}
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func (f *fieldPath) add(i int) {
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f.vals[f.last] += i
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}
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func (f *fieldPath) push(i int) {
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f.last++
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f.vals[f.last] = i
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}
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func (f *fieldPath) pop() int {
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f.last--
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return f.vals[f.last+1]
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}
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func (f *fieldPath) replaceAll(fn func(v int) int) {
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for i := 0; i <= f.last; i++ {
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f.vals[i] = fn(f.vals[i])
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}
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}
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// reads the sequence of id values off of the provided bit reader given the
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// huffman tree of fieldpath ops rooted at the node n
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func (f *fieldPath) read(br bit.Reader, n node) error {
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f.last = 0
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for fn := walk(n, br); fn != nil; fn = walk(n, br) {
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if err := br.Err(); err != nil {
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return fmt.Errorf("unable to read fieldpath: reader error: %v", err)
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}
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fn(f, br)
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}
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return nil
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}
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// the subslice of valid index values that has been read on the fieldpath
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func (f *fieldPath) path() []int {
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return f.vals[:f.last+1]
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}
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