Initial commit

.github/dependabot.yaml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"
+
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/codeql-analysis.yaml

@@ -0,0 +1,70 @@
+# For most projects, this workflow file will not need changing; you simply need
+# to commit it to your repository.
+#
+# You may wish to alter this file to override the set of languages analyzed,
+# or to provide custom queries or build logic.
+#
+# ******** NOTE ********
+# We have attempted to detect the languages in your repository. Please check
+# the `language` matrix defined below to confirm you have the correct set of
+# supported CodeQL languages.
+#
+name: "CodeQL"
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [ main ]
+  schedule:
+    - cron: '41 14 * * 2'
+
+jobs:
+  analyze:
+    name: Analyze
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      security-events: write
+
+    strategy:
+      fail-fast: false
+      matrix:
+        language: [ 'go' ]
+        # CodeQL supports [ 'cpp', 'csharp', 'go', 'java', 'javascript', 'python', 'ruby' ]
+        # Learn more about CodeQL language support at https://git.io/codeql-language-support
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+
+    # Initializes the CodeQL tools for scanning.
+    - name: Initialize CodeQL
+      uses: github/codeql-action/init@v3
+      with:
+        languages: ${{ matrix.language }}
+        # If you wish to specify custom queries, you can do so here or in a config file.
+        # By default, queries listed here will override any specified in a config file.
+        # Prefix the list here with "+" to use these queries and those in the config file.
+        # queries: ./path/to/local/query, your-org/your-repo/queries@main
+
+    # Autobuild attempts to build any compiled languages  (C/C++, C#, or Java).
+    # If this step fails, then you should remove it and run the build manually (see below)
+    - name: Autobuild
+      uses: github/codeql-action/autobuild@v3
+
+    # ℹ️ Command-line programs to run using the OS shell.
+    # 📚 https://git.io/JvXDl
+
+    # ✏️ If the Autobuild fails above, remove it and uncomment the following three lines
+    #    and modify them (or add more) to build your code if your project
+    #    uses a compiled language
+
+    #- run: |
+    #   make bootstrap
+    #   make release
+
+    - name: Perform CodeQL Analysis
+      uses: github/codeql-action/analyze@v3

.github/workflows/coverage.yaml

@@ -0,0 +1,14 @@
+name: coverage
+on: push
+
+jobs:
+  coverage:
+    runs-on: ubuntu-latest
+    name: Go test coverage
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: "stable"
+      - run: go test -coverprofile=coverage.txt -covermode=atomic
+      - uses: codecov/codecov-action@v4

.github/workflows/release.yaml

@@ -0,0 +1,36 @@
+name: goreleaser
+
+on:
+  push:
+    tags:
+      - "v*"
+
+permissions:
+  contents: write
+
+jobs:
+  test: 
+    uses: ./.github/workflows/test.yaml
+    secrets: inherit
+  goreleaser:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+      -
+        name: Setup
+        uses: actions/setup-go@v5
+        with:
+          go-version: '>=1.22'
+      -
+        name: Run GoReleaser
+        uses: goreleaser/goreleaser-action@v5
+        with:
+          distribution: goreleaser
+          version: ${{ env.GITHUB_REF_NAME }}
+          args: release --rm-dist
+        env:
+          GITHUB_TOKEN: ${{ secrets.WEIGHTEDOPTION_RELEASE_TOKEN }}

.github/workflows/test.yaml

@@ -0,0 +1,30 @@
+name: test
+
+on:
+  push:
+    branches:
+      - '*'
+    tags-ignore:
+      - '*'
+  pull_request:
+  workflow_call:
+
+jobs:
+    test:
+        runs-on: ubuntu-latest
+        name: Tests
+        steps:
+          -
+            name: Checkout
+            uses: actions/checkout@v3
+            with:
+              fetch-depth: 0
+          -
+            name: Setup
+            uses: actions/setup-go@v5
+            with:
+              go-version: '>=1.22'
+
+          - 
+            name: Test
+            run: go test --race --shuffle on ./...

.gitignore

@@ -19,3 +19,9 @@
 
 # Go workspace file
 go.work
+
+# MacOS
+.DS_Store
+
+# GoLand
+.idea/

.goreleaser.yaml

@@ -0,0 +1,16 @@
+before:
+  hooks:
+    - go mod tidy
+
+builds:
+  - skip: true
+
+release:
+  prerelease: auto
+
+changelog:
+  sort: asc
+  filters:
+    exclude:
+      - '^docs:'
+      - '^test:'

README.md

@@ -1,2 +1,43 @@
 # weightedoption
+
 A Go package for weighted random option selection 
+
+## Example Usage
+
+```go
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/eljamo/weightedoption"
+)
+
+// Simulates 100 chances for dropping a raid exotic weapon from a Destiny which has a 5% drop chance when a player completes the raid
+func main() {
+	s, err := weightedoption.NewSelector(
+		weightedoption.NewOption('🔫', 5),
+		weightedoption.NewOption('❌', 95),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	chances := make([]rune, 30)
+	for i := 0; i < len(chances); i++ {
+		chances[i] = s.Select()
+	}
+	fmt.Println(string(chances))
+
+	tally := make(map[rune]int)
+	for _, c := range chances {
+		tally[c]++
+	}
+
+	_, err = fmt.Printf("\n🔫: %d\t❌ %d\n", tally['🔫'], tally['❌'])
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+```

go.mod

@@ -0,0 +1,3 @@
+module github.com/eljamo/weightedoption
+
+go 1.22.1

weightedoption.go

@@ -0,0 +1,132 @@
+package weightedoption
+
+import (
+	"errors"
+	"math"
+	"math/rand/v2"
+	"sort"
+)
+
+var (
+	ErrWeightOverflow = errors.New("sum of Option weights exceeds total")
+	ErrNoValidOptions = errors.New("0 Option(s) with Weight >= 1")
+)
+
+// WeightIntegerConstraint is a type constraint for the Weight field of the Option struct.
+type WeightIntegerConstraint interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 | ~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
+}
+
+// Option is a struct that holds a data value and its associated weight.
+type Option[DataType any, WeightIntegerType WeightIntegerConstraint] struct {
+	Data   DataType
+	Weight WeightIntegerType
+}
+
+// NewOption creates a new Option.
+func NewOption[DataType any, WeightIntegerType WeightIntegerConstraint](
+	data DataType,
+	weight WeightIntegerType,
+) Option[DataType, WeightIntegerType] {
+	return Option[DataType, WeightIntegerType]{Data: data, Weight: weight}
+}
+
+// SearchIntsFuncSignature is the signature of the function used to search for an integer in a sorted slice of integers.
+type SearchIntsFuncSignature func(runningTotalWeights []int, randInt int) int
+
+// Selector is a struct that holds a slice of Options and their cumulative weights.
+type Selector[DataType any, WeightIntegerType WeightIntegerConstraint] struct {
+	options             []Option[DataType, WeightIntegerType]
+	runningTotalWeights []int
+	totalWeight         int
+	searchIntsFunc      SearchIntsFuncSignature
+}
+
+// NewSelector creates a new Selector.
+func NewSelector[DataType any, WeightIntegerType WeightIntegerConstraint](
+	options ...Option[DataType, WeightIntegerType],
+) (*Selector[DataType, WeightIntegerType], error) {
+	var filteredOptions []Option[DataType, WeightIntegerType]
+	for _, opt := range options {
+		if opt.Weight > 0 {
+			filteredOptions = append(filteredOptions, opt)
+		}
+	}
+
+	sort.Slice(filteredOptions, func(i, j int) bool {
+		return filteredOptions[i].Weight < filteredOptions[j].Weight
+	})
+
+	runningTotalWeights := make([]int, len(filteredOptions))
+	totalWeight := 0
+
+	for i, opt := range filteredOptions {
+		if uint(opt.Weight) >= math.MaxInt {
+			return nil, ErrWeightOverflow
+		}
+
+		weight := int(opt.Weight)
+		if weight > math.MaxInt-totalWeight {
+			return nil, ErrWeightOverflow
+		}
+
+		totalWeight += weight
+		runningTotalWeights[i] = totalWeight
+	}
+
+	if totalWeight < 1 {
+		return nil, ErrNoValidOptions
+	}
+
+	return &Selector[DataType, WeightIntegerType]{
+		options:             filteredOptions,
+		runningTotalWeights: runningTotalWeights,
+		totalWeight:         totalWeight,
+		searchIntsFunc:      searchInts,
+	}, nil
+}
+
+// NewSelectorWithCustomSearchIntsFunc creates a new Selector with a custom searchIntsFunc.
+func NewSelectorWithCustomSearchIntsFunc[DataType any, WeightIntegerType WeightIntegerConstraint](
+	searchIntsFunc SearchIntsFuncSignature,
+	options ...Option[DataType, WeightIntegerType],
+) (*Selector[DataType, WeightIntegerType], error) {
+	selector, err := NewSelector(options...)
+	if err != nil {
+		return nil, err
+	}
+
+	selector.searchIntsFunc = searchIntsFunc
+	return selector, nil
+}
+
+// NewSelectorUsingSortSearchInts creates a new Selector using the sort.SearchInts function.
+func NewSelectorUsingSortSearchInts[DataType any, WeightIntegerType WeightIntegerConstraint](
+	options ...Option[DataType, WeightIntegerType],
+) (*Selector[DataType, WeightIntegerType], error) {
+	return NewSelectorWithCustomSearchIntsFunc(sort.SearchInts, options...)
+}
+
+// Select returns a single option from the Selector.
+func (s Selector[DataType, WeightIntegerType]) Select() DataType {
+	r := rand.IntN(s.totalWeight) + 1
+	i := s.searchIntsFunc(s.runningTotalWeights, r)
+	return s.options[i].Data
+}
+
+// searchInts searches for the index of the first element in runningTotalWeights
+// that is greater than or equal to randInt. The slice must be sorted in
+// ascending order.
+func searchInts(runningTotalWeights []int, randInt int) int {
+	start, end := 0, len(runningTotalWeights)
+	for start < end {
+		mid := int(uint(start+end) >> 1)
+		if runningTotalWeights[mid] < randInt {
+			start = mid + 1
+		} else {
+			end = mid
+		}
+	}
+
+	return start
+}