Automatic version switching in bash

.gitattributes

@@ -0,0 +1,4 @@
+/nvs text eol=lf
+/nvs.sh text eol=lf
+/nvs.cmd text eol=crlf
+/nvs.ps1 text eol=crlf

README.md

@@ -21,7 +21,7 @@ A Windows Installer (MSI) package is available from the [NVS releases page on Gi
 
 ### Mac, Linux
 Specify the installation path, clone the repo, and *source* the `install` command:
-```sh
+```
 export NVS_HOME="$HOME/.nvs"
 git clone https://github.com/jasongin/nvs "$NVS_HOME"
 . "$NVS_HOME/nvs.sh" install
@@ -40,6 +40,7 @@ Command | Description
 `nvs rm <version>`               | Remove a node version
 `nvs migrate <fromver> [tover]`  | Migrate global modules
 `nvs use <version>`              | Use a node version in the current shell
+`nvs auto [on/off]`              | Automatically switch based on cwd
 `nvs run <ver> <js> [args...]`   | Run a script using a node version
 `nvs exec <ver> <exe> [args...]` | Run an executable using a node version
 `nvs which [version]`            | Show the path to a node version binary
@@ -68,9 +69,10 @@ $ nvs remote
 default  node
 nightly  https://nodejs.org/download/nightly/
 node     https://nodejs.org/dist/
-$ nvs lsr nightly
-7.0.0-nightly20161006bd0bedb86a ...
-$ nvs add nightly/7.0.0-nightly20161006bd0bedb86a
+$ nvs lsr nightly 7
+7.0.1-nightly2016102527e1749dcb
+...
+$ nvs add nightly/7.0.1-nightly2016102527e1749dcb
 ```
 ## Aliases
 An alias refers to a combination of a remote name and a semantic version. (Processor architectures are not aliased.) When setting an alias, the remote name may be omitted, in which case the alias refers to the default remote. An alias may be used in place of a version string in any of the other commands.
@@ -85,6 +87,23 @@ $ nvs which myalias
 $ nvs which myalias/32
 ~/.nvs/node/6.7.0/x86/bin/node
 ```
+## Automatic switching per directory
+In either Bash or PowerShell, NVS can automatically switch the node version in the current shell as you change directories. This function is disabled by default; to enable it run `nvs auto on`. Afterward, whenver you `cd` or `pushd` under a directory containing a `.node-version` file then NVS will automatically switch the node version accordingly, downloading a new version if necessary. When you `cd` out to a directory with no `.node-version` file anywhere above it, then the default (linked) version is restored, if any.
+```
+~$ nvs link 6.9.1
+~/.nvs/default -> ~/.nvs/node/6.9.1/x64
+~$ nvs use
+PATH += ~/.nvs/default/bin
+~$ nvs auto on
+~$ cd myproject
+PATH -= ~/.nvs/default/bin
+PATH += ~/.nvs/node/4.6.1/x64/bin
+~/myproject$ cd ..
+PATH -= ~/.nvs/node/4.6.1/x64/bin
+PATH += ~/.nvs/default/bin
+```
+*This feature is not available in Windows Command Prompt. Use PowerShell instead.*
+
 # How it works
 
 ## Bootstrapping node

lib/auto.js

@@ -69,25 +69,44 @@ function enableAutoSwitch(enable) {
     }
 
     let psScriptFile = path.join(path.resolve(__dirname, '..'), 'nvs.ps1');
-    // let shScriptFile = path.join(path.resolve(__dirname, '..'), 'nvs.sh');
 
-    require('./postScript').generate(null, {
-        '.PS1': [
-            // Patch the function that is invoked every time PowerShell shows a prompt.
-            // Export the function from the script using a dynamic module; this
-            // does NOT require the script to be sourced.
-            'if (-not $env:NVS_ORIGINAL_PROMPT) { ',
-            '    $env:NVS_ORIGINAL_PROMPT = $(Get-Content function:\\prompt)',
-            '}',
-            'New-Module -Script {',
-            enable
-                ? 'function prompt { . "' + psScriptFile + '" "prompt" }'
-                : 'function prompt { Invoke-Expression $env:NVS_ORIGINAL_PROMPT }',
-            'Export-ModuleMember -Function prompt',
-            '} > $null',
-        ],
-        '.SH': null, // TODO: define cd(), pushd(), popd() functions
-    });
+    if (enable) {
+        require('./postScript').generate(null, {
+            '.PS1': [
+                // Patch the function that is invoked every time PowerShell shows a prompt.
+                // Export the function from the script using a dynamic module; this
+                // does NOT require the script to be sourced.
+                'if (-not $env:NVS_ORIGINAL_PROMPT) { ',
+                '    $env:NVS_ORIGINAL_PROMPT = $(Get-Content function:\\prompt)',
+                '}',
+                'New-Module -Script {',
+                '    function prompt { . "' + psScriptFile + '" "prompt" }',
+                '    Export-ModuleMember -Function prompt',
+                '} > $null',
+            ],
+            '.SH': [
+                'cd () { builtin cd "$@" && nvs cd; }',
+                'pushd () { builtin pushd "$@" && nvs cd; }',
+                'popd () { builtin popd "$@" && nvs cd; }',
+            ],
+        });
+    } else {
+        require('./postScript').generate(null, {
+            '.PS1': [
+                'if ($env:NVS_ORIGINAL_PROMPT) { ',
+                '    New-Module -Script {',
+                '        function prompt { Invoke-Expression $env:NVS_ORIGINAL_PROMPT }',
+                '        Export-ModuleMember -Function prompt',
+                '    } > $null',
+                '}',
+            ],
+            '.SH': [
+                'cd () { builtin cd "$@"; }',
+                'pushd () { builtin pushd "$@"; }',
+                'popd () { builtin popd "$@"; }',
+            ],
+        });
+    }
 }
 
 module.exports = {

lib/install.js

@@ -6,6 +6,7 @@ const Error = require('./error');
 let nvsUse = require('./use');
 let nvsLink = require('./link');
 let nvsPostScript = require('./postScript');
+let nvsAuto = require('./auto');
 
 const isWindows = process.platform === 'win32';
 
@@ -41,6 +42,8 @@ function install() {
 
 function uninstall() {
     let result = [];
+
+    nvsAuto.enableAutoSwitch(false);
     result = result.concat(nvsUse.use(null));
     result = result.concat(nvsLink.unlink());
 

lib/postScript.js

@@ -4,6 +4,9 @@ const os = require('os');
 
 const canUpdateEnv = !process.env['NVS_EXECUTE'];
 
+// Lines may be accumulated across multiple calls to generate().
+let postScriptLines = [];
+
 /**
  * Generates a shell script to be invoked after the main (Node.js) script finishes.
  * The NVS shim shell scripts take care of invoking the generated script and
@@ -18,7 +21,6 @@ function generate(exportVars, additionalLines) {
     }
 
     let envVars = Object.keys(exportVars || {});
-    let postScriptLines = [];
     let postScriptFile = process.env['NVS_POSTSCRIPT'];
     if (!postScriptFile) {
         throw new Error('NVS_POSTSCRIPT environment variable not set.');

lib/use.js

@@ -139,6 +139,9 @@ function use(version, skipUpdateShellEnv) {
                 version = null;
             } else {
                 pathEntries.splice(i--, 1);
+                if (!isWindows) {
+                    pathEntry = path.join(pathEntry, 'bin');
+                }
                 result.push('PATH -= ' + homePath(pathEntry));
                 saveChanges = true;
             }

nvs.sh

@@ -56,9 +56,32 @@ nvs() {
         echo ""
     fi
 
-    # Forward args to the main JavaScript file.
-    command "${BOOTSTRAP_NODE_PATH}" "${NVS_ROOT}/lib/main.js" "$@"
-    local EXIT_CODE=$?
+    local EXIT_CODE
+
+    # Check if invoked as a CD function that enables auto-switching.
+    if [[ "$@" == "cd" ]]; then
+        # Find the nearest .node-version file in current or parent directories
+        local DIR=$PWD
+        while [[ "$DIR" != "" && ! -e "$DIR/.node-version" ]]; do
+            if [[ "$DIR" == "/" ]]; then
+                DIR=
+            else
+                DIR=$(dirname "$DIR")
+            fi
+        done
+
+        # If it's different from the last auto-switched directory, then switch.
+        if [[ "$DIR" != "$NVS_AUTO_DIRECTORY" ]]; then
+            command "${BOOTSTRAP_NODE_PATH}" "${NVS_ROOT}/lib/main.js" auto
+            EXIT_CODE=$?
+        fi
+
+        export NVS_AUTO_DIRECTORY=$DIR
+    else
+        # Forward args to the main JavaScript file.
+        command "${BOOTSTRAP_NODE_PATH}" "${NVS_ROOT}/lib/main.js" "$@"
+        EXIT_CODE=$?
+    fi
 
     # Call the post-invocation script if it is present, then delete it.
     # This allows the invocation to potentially modify the caller's environment (e.g. PATH)