Examples/Invoke-SnakeDemo.ps1
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Import-Module "$PSScriptRoot/../Elm.psd1" -Force # --------------------------------------------------------------------------- # Snake demo # Classic Snake game in the terminal. # Demonstrates: timer + key subscriptions together, game loop state, grid render. # # Controls: # Arrow keys / WASD - change direction # Space - start / pause # R - restart # Q - quit # --------------------------------------------------------------------------- $script:COLS = 30 # playfield columns (each cell = 1 char) $script:ROWS = 18 # playfield rows $script:SPEED = 150 # ms per tick function Get-RandomFood { param([object[]]$Snake) $occupied = @{} foreach ($seg in $Snake) { $occupied["$($seg.X),$($seg.Y)"] = $true } $free = [System.Collections.Generic.List[object]]::new() for ($y = 0; $y -lt $script:ROWS; $y++) { for ($x = 0; $x -lt $script:COLS; $x++) { if (-not $occupied.ContainsKey("$x,$y")) { $free.Add([PSCustomObject]@{ X = $x; Y = $y }) } } } if ($free.Count -eq 0) { return $null } $free[(Get-Random -Maximum $free.Count)] } function New-SnakeModel { $head = [PSCustomObject]@{ X = 14; Y = 9 } $body = @( [PSCustomObject]@{ X = 13; Y = 9 } [PSCustomObject]@{ X = 12; Y = 9 } ) $snake = @($head) + $body [PSCustomObject]@{ Snake = $snake Dir = 'Right' NextDir = 'Right' Food = (Get-RandomFood -Snake $snake) Score = 0 Running = $false GameOver = $false } } $initFn = { [PSCustomObject]@{ Model = New-SnakeModel Cmd = $null } } $updateFn = { param($msg, $model) switch ($msg) { 'Tick' { if (-not $model.Running -or $model.GameOver) { return [PSCustomObject]@{ Model = $model; Cmd = $null } } $dir = $model.NextDir $snake = @($model.Snake) $head = $snake[0] $newHead = switch ($dir) { 'Up' { [PSCustomObject]@{ X = $head.X; Y = $head.Y - 1 } } 'Down' { [PSCustomObject]@{ X = $head.X; Y = $head.Y + 1 } } 'Left' { [PSCustomObject]@{ X = $head.X - 1; Y = $head.Y } } 'Right' { [PSCustomObject]@{ X = $head.X + 1; Y = $head.Y } } } # Wall collision $hitWall = ($newHead.X -lt 0 -or $newHead.X -ge $script:COLS -or $newHead.Y -lt 0 -or $newHead.Y -ge $script:ROWS) # Self collision $hitSelf = $false foreach ($seg in $snake) { if ($seg.X -eq $newHead.X -and $seg.Y -eq $newHead.Y) { $hitSelf = $true; break } } if ($hitWall -or $hitSelf) { $newModel = [PSCustomObject]@{ Snake = $model.Snake Dir = $dir NextDir = $dir Food = $model.Food Score = $model.Score Running = $false GameOver = $true } return [PSCustomObject]@{ Model = $newModel; Cmd = $null } } # Eat food? $ate = ($null -ne $model.Food -and $newHead.X -eq $model.Food.X -and $newHead.Y -eq $model.Food.Y) $newSnake = if ($ate) { @($newHead) + $snake # keep tail (grow) } else { @($newHead) + $snake[0..($snake.Count - 2)] # drop tail } $newFood = if ($ate) { Get-RandomFood -Snake $newSnake } else { $model.Food } $newScore = if ($ate) { $model.Score + 1 } else { $model.Score } $newModel = [PSCustomObject]@{ Snake = $newSnake Dir = $dir NextDir = $dir Food = $newFood Score = $newScore Running = $true GameOver = $false } return [PSCustomObject]@{ Model = $newModel; Cmd = $null } } 'Up' { $opp = 'Down' } 'Down' { $opp = 'Up' } 'Left' { $opp = 'Right' } 'Right' { $opp = 'Left' } } # Direction change (only if not opposite to current) if ($msg -in @('Up','Down','Left','Right')) { $opp = switch ($msg) { 'Up' { 'Down' } 'Down' { 'Up' } 'Left' { 'Right' } 'Right' { 'Left' } } if ($model.Dir -ne $opp) { $newModel = [PSCustomObject]@{ Snake = $model.Snake Dir = $model.Dir NextDir = $msg Food = $model.Food Score = $model.Score Running = $model.Running GameOver = $model.GameOver } return [PSCustomObject]@{ Model = $newModel; Cmd = $null } } return [PSCustomObject]@{ Model = $model; Cmd = $null } } switch ($msg) { 'Toggle' { if ($model.GameOver) { return [PSCustomObject]@{ Model = $model; Cmd = $null } } $newModel = [PSCustomObject]@{ Snake = $model.Snake Dir = $model.Dir NextDir = $model.NextDir Food = $model.Food Score = $model.Score Running = -not $model.Running GameOver = $model.GameOver } return [PSCustomObject]@{ Model = $newModel; Cmd = $null } } 'Restart' { return [PSCustomObject]@{ Model = (New-SnakeModel); Cmd = $null } } 'Quit' { return [PSCustomObject]@{ Model = $model Cmd = [PSCustomObject]@{ Type = 'Quit' } } } } [PSCustomObject]@{ Model = $model; Cmd = $null } } $viewFn = { param($model) $snake = @($model.Snake) $snakeSet = @{} foreach ($seg in $snake) { $snakeSet["$($seg.X),$($seg.Y)"] = $true } # Build the grid as rows of text $headStyle = New-ElmStyle -Foreground 'BrightGreen' -Bold $bodyStyle = New-ElmStyle -Foreground 'Green' $foodStyle = New-ElmStyle -Foreground 'BrightRed' -Bold $wallStyle = New-ElmStyle -Foreground 'BrightBlack' $titleStyle = New-ElmStyle -Foreground 'BrightCyan' -Bold $scoreStyle = New-ElmStyle -Foreground 'BrightWhite' $hintStyle = New-ElmStyle -Foreground 'BrightBlack' $deadStyle = New-ElmStyle -Foreground 'BrightRed' -Bold $head = $snake[0] $border = '+' + ('-' * $script:COLS) + '+' $children = [System.Collections.Generic.List[object]]::new() $children.Add((New-ElmText -Content 'Snake' -Style $titleStyle)) $children.Add((New-ElmText -Content "Score: $($model.Score)" -Style $scoreStyle)) $children.Add((New-ElmText -Content $border -Style $wallStyle)) for ($y = 0; $y -lt $script:ROWS; $y++) { $rowChars = [System.Text.StringBuilder]::new() $null = $rowChars.Append('|') for ($x = 0; $x -lt $script:COLS; $x++) { $key = "$x,$y" if ($x -eq $head.X -and $y -eq $head.Y) { $null = $rowChars.Append('@') } elseif ($snakeSet.ContainsKey($key)) { $null = $rowChars.Append('o') } elseif ($null -ne $model.Food -and $x -eq $model.Food.X -and $y -eq $model.Food.Y) { $null = $rowChars.Append('*') } else { $null = $rowChars.Append(' ') } } $null = $rowChars.Append('|') $children.Add((New-ElmText -Content $rowChars.ToString() -Style $wallStyle)) } $children.Add((New-ElmText -Content $border -Style $wallStyle)) if ($model.GameOver) { $children.Add((New-ElmText -Content '' )) $children.Add((New-ElmText -Content "GAME OVER Score: $($model.Score)" -Style $deadStyle)) $children.Add((New-ElmText -Content '[R] Restart [Q] Quit' -Style $hintStyle)) } elseif ($model.Running) { $children.Add((New-ElmText -Content '[Arrow/WASD] steer [Space] pause [Q] quit' -Style $hintStyle)) } else { $children.Add((New-ElmText -Content '[Space] Start [Q] Quit' -Style $hintStyle)) } New-ElmBox -Children $children.ToArray() } $subFn = { param($model) $subs = [System.Collections.Generic.List[object]]::new() # Quit always works $subs.Add((New-ElmKeySub -Key 'Q' -Handler { 'Quit' })) if ($model.GameOver) { $subs.Add((New-ElmKeySub -Key 'R' -Handler { 'Restart' })) } else { $subs.Add((New-ElmKeySub -Key 'Space' -Handler { 'Toggle' })) $subs.Add((New-ElmKeySub -Key 'R' -Handler { 'Restart' })) $subs.Add((New-ElmKeySub -Key 'UpArrow' -Handler { 'Up' })) $subs.Add((New-ElmKeySub -Key 'DownArrow' -Handler { 'Down' })) $subs.Add((New-ElmKeySub -Key 'LeftArrow' -Handler { 'Left' })) $subs.Add((New-ElmKeySub -Key 'RightArrow' -Handler { 'Right' })) $subs.Add((New-ElmKeySub -Key 'W' -Handler { 'Up' })) $subs.Add((New-ElmKeySub -Key 'S' -Handler { 'Down' })) $subs.Add((New-ElmKeySub -Key 'A' -Handler { 'Left' })) $subs.Add((New-ElmKeySub -Key 'D' -Handler { 'Right' })) if ($model.Running) { $subs.Add((New-ElmTimerSub -IntervalMs $script:SPEED -Handler { 'Tick' })) } } return $subs.ToArray() } function Invoke-SnakeDemo { <# .SYNOPSIS Classic Snake game in the terminal. .DESCRIPTION Arrow keys / WASD to steer. Space to start/pause. R to restart. Q to quit. Demonstrates combined timer + key subscriptions in the Elm architecture. .NOTES Requires the Elm module and a terminal at least 32 columns wide. Run from Examples: . .\Invoke-SnakeDemo.ps1; Invoke-SnakeDemo #> [CmdletBinding()] param() Start-ElmProgram -InitFn $initFn -UpdateFn $updateFn -ViewFn $viewFn -SubscriptionFn $subFn } Invoke-SnakeDemo |