109 lines
2.2 KiB
Go
109 lines
2.2 KiB
Go
package matrix
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import (
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"strings"
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"github.com/drone/drone/Godeps/_workspace/src/gopkg.in/yaml.v2"
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)
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const (
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limitTags = 10
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limitAxis = 25
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)
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// Matrix represents the build matrix.
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type Matrix map[string][]string
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// Axis represents a single permutation of entries
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// from the build matrix.
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type Axis map[string]string
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// String returns a string representation of an Axis as
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// a comma-separated list of environment variables.
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func (a Axis) String() string {
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var envs []string
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for k, v := range a {
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envs = append(envs, k+"="+v)
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}
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return strings.Join(envs, " ")
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}
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// Parse parses the Matrix section of the yaml file and
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// returns a list of axis.
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func Parse(raw string) ([]Axis, error) {
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matrix, err := parseMatrix(raw)
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if err != nil {
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return nil, err
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}
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// if not a matrix build return an array
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// with just the single axis.
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if len(matrix) == 0 {
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return nil, nil
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}
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return Calc(matrix), nil
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}
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// Calc calculates the permutations for th build matrix.
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//
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// Note that this method will cap the number of permutations
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// to 25 to prevent an overly expensive calculation.
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func Calc(matrix Matrix) []Axis {
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// calculate number of permutations and
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// extract the list of tags
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// (ie go_version, redis_version, etc)
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var perm int
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var tags []string
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for k, v := range matrix {
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perm *= len(v)
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if perm == 0 {
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perm = len(v)
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}
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tags = append(tags, k)
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}
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// structure to hold the transformed
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// result set
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axisList := []Axis{}
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// for each axis calculate the uniqe
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// set of values that should be used.
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for p := 0; p < perm; p++ {
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axis := map[string]string{}
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decr := perm
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for i, tag := range tags {
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elems := matrix[tag]
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decr = decr / len(elems)
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elem := p / decr % len(elems)
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axis[tag] = elems[elem]
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// enforce a maximum number of tags
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// in the build matrix.
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if i > limitTags {
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break
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}
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}
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// append to the list of axis.
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axisList = append(axisList, axis)
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// enforce a maximum number of axis
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// that should be calculated.
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if p > limitAxis {
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break
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}
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}
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return axisList
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}
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// helper function to parse the Matrix data from
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// the raw yaml file.
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func parseMatrix(raw string) (Matrix, error) {
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data := struct {
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Matrix map[string][]string
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}{}
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err := yaml.Unmarshal([]byte(raw), &data)
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return data.Matrix, err
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}
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