cmd: add support for ENV command (#469)

* cmd: start initial work on env key val

* restore demo gif

* restore

* oops

* add comments

* readme: add env command instructions

* Update command.go

* Update README.md

* Apply suggestions from code review

* Update command.go

* Update command.go

---------

Co-authored-by: Maas Lalani <[email protected]>

Author: Delta456

README.md

@@ -221,6 +221,7 @@ There are a few basic types of VHS commands:
 * [`Screenshot`](#screenshot): screenshot the current frame
 * [`Copy/Paste`](#copy--paste): copy and paste text from clipboard.
 * [`Source`](#source): source commands from another tape
+* [`Env <Key> Value`](#env): set environment variables
 
 ### Output
 
@@ -738,6 +739,18 @@ Sleep 500ms
 Paste
 ```
 
+### Env
+
+`Env` command sets the environment variable via key-value pair.
+
+```elixir
+Env HELLO WORLD
+
+Type "echo $HELLO"
+Enter
+Sleep 3s
+```
+
 
 ### Source
 

command.go

@@ -64,6 +64,7 @@ var CommandFuncs = map[parser.CommandType]CommandFunc{
 	token.SCREENSHOT: ExecuteScreenshot,
 	token.COPY:       ExecuteCopy,
 	token.PASTE:      ExecutePaste,
+	token.ENV:        ExecuteEnv,
 }
 
 // ExecuteNoop is a no-op command that does nothing.
@@ -248,6 +249,11 @@ func ExecuteCopy(c parser.Command, _ *VHS) {
 	_ = clipboard.WriteAll(c.Args)
 }
 
+// ExecuteEnv sets env with given key-value pair.
+func ExecuteEnv(c parser.Command, _ *VHS) {
+	_ = os.Setenv(c.Options, c.Args)
+}
+
 // ExecutePaste pastes text from the clipboard.
 func ExecutePaste(_ parser.Command, v *VHS) {
 	clip, err := clipboard.ReadAll()

command_test.go

@@ -8,12 +8,12 @@ import (
 )
 
 func TestCommand(t *testing.T) {
-	const numberOfCommands = 27
+	const numberOfCommands = 28
 	if len(parser.CommandTypes) != numberOfCommands {
 		t.Errorf("Expected %d commands, got %d", numberOfCommands, len(parser.CommandTypes))
 	}
 
-	const numberOfCommandFuncs = 27
+	const numberOfCommandFuncs = 28
 	if len(CommandFuncs) != numberOfCommandFuncs {
 		t.Errorf("Expected %d commands, got %d", numberOfCommandFuncs, len(CommandFuncs))
 	}

evaluator.go

@@ -32,6 +32,9 @@ func Evaluate(ctx context.Context, tape string, out io.Writer, opts ...Evaluator
 		if cmd.Type == token.SET && cmd.Options == "Shell" {
 			Execute(cmd, &v)
 		}
+		if cmd.Type == token.ENV {
+			Execute(cmd, &v)
+		}
 	}
 
 	// Start things up

parser/parser.go

@@ -51,6 +51,7 @@ var CommandTypes = []CommandType{ //nolint: deadcode
 	token.SCREENSHOT,
 	token.COPY,
 	token.PASTE,
+	token.ENV,
 }
 
 // String returns the string representation of the command.
@@ -177,6 +178,8 @@ func (p *Parser) parseCommand() Command {
 		return p.parseCopy()
 	case token.PASTE:
 		return p.parsePaste()
+	case token.ENV:
+		return p.parseEnv()
 	default:
 		p.errors = append(p.errors, NewError(p.cur, "Invalid command: "+p.cur.Literal))
 		return Command{Type: token.ILLEGAL}
@@ -577,6 +580,26 @@ func (p *Parser) parsePaste() Command {
 	return cmd
 }
 
+// parseEnv parses Env command
+// Env command takes in a key-value pair which is set.
+//
+// Env key "value"
+func (p *Parser) parseEnv() Command {
+	cmd := Command{Type: token.ENV}
+
+	cmd.Options = p.peek.Literal
+	p.nextToken()
+
+	if p.peek.Type != token.STRING {
+		p.errors = append(p.errors, NewError(p.peek, p.cur.Literal+" expects string"))
+	}
+
+	cmd.Args = p.peek.Literal
+	p.nextToken()
+
+	return cmd
+}
+
 // parseSource parses source command.
 // Source command takes a tape path to include in current tape.
 //

token/token.go

@@ -72,6 +72,7 @@ const (
 	COPY            = "COPY"
 	PASTE           = "PASTE"
 	SHELL           = "SHELL"
+	ENV             = "ENV"
 	FONT_FAMILY     = "FONT_FAMILY" //nolint:revive
 	FONT_SIZE       = "FONT_SIZE"   //nolint:revive
 	FRAMERATE       = "FRAMERATE"
@@ -148,6 +149,7 @@ var Keywords = map[string]Type{
 	"Screenshot":    SCREENSHOT,
 	"Copy":          COPY,
 	"Paste":         PASTE,
+	"Env":           ENV,
 }
 
 // IsSetting returns whether a token is a setting.