Initial bits for integrating the LSP API.

Author: christianparpart

README.md

@@ -204,6 +204,71 @@ The low-level API is as follows:
 
 For examples how to use them, please refer to the README of the above mentioned solc-js releases.
 
+#### Language Server Mode
+
+Since version 0.8.11, the solidity compiler natively supports the
+language server protocol. With solc-js, you can now use it as follows:
+
+```javascript
+var solc = require('solc');
+
+// Callback to be invoked when additional files have to be opened during
+// source code analysis stage.
+//
+// This function behaves similar to the compilation file reader callback.
+function fileReadCallback(path)
+{
+    if ('path' === 'file:///project/lib.sol') {
+        return {
+            contents: 'library L { function f() internal returns (uint) { return 7; } }';
+        };
+    }
+    else
+        return { error: 'File not found' };
+}
+
+// Put solcjs into LSP mode.
+// Needs to be called only once before the actual LSP I/O calls.
+solc.lspStart(fileReadCallback);
+
+// Send some LSP JSON-RPC message and optionally receive a reply.
+var lspInitializationMessage = {
+    'jsonrpc': '2.0',
+    'method': 'initialize',
+    'params': {
+        'rootUri': 'file:///project/',
+        'capabilities': {
+            'textDocument': {
+                'publishDiagnostics': {'relatedInformation': true}
+            },
+            'workspace': {
+                'applyEdit': true,
+                'configuration': true,
+                'didChangeConfiguration': {'dynamicRegistration': true},
+                'workspaceEdit': {'documentChanges': true},
+                'workspaceFolders': true
+            }
+        }
+    }
+};
+solc.lspSendReceive(JSON.stringify(lspInitializationMessage)));
+solc.lspSendReceive(JSON.stringify({'jsonrpc': '2.0', 'method': 'initialized'}));
+
+// Now, with the LSP server, being set up the following
+// can be called as often as needed.
+function lspRoundtrip(jsonRpcInputObject)
+{
+    return JSON.parse(solc.lspSendReceive(JSON.stringify(jsonRpcInputObject)));
+}
+```
+
+This is a low level API endpoint for use by language server clients,
+such as Visual Studio Code, or any other editor.
+In order to know what you can pass in and what can come out,
+it is highly recommended to have a look at:
+
+  https://microsoft.github.io/language-server-protocol/specification
+
 ### Using with Electron
 
 **Note:**

wrapper.ts

@@ -92,6 +92,25 @@ function setupMethods (soljson) {
     };
   };
 
+  let lspStart = null;
+  if ('_solidity_lsp_start' in soljson) {
+    const wrappedLspStart = soljson.cwrap('solidity_lsp_start', 'int', []);
+    lspStart = function (callbacks) {
+      return runWithCallbacks(callbacks, wrappedLspStart, []);
+    };
+  }
+
+  let lspSendReceive = null;
+  if ('_solidity_lsp_send_receive' in soljson) {
+    const wrappedLspSendReceive = soljson.cwrap('solidity_lsp_send_receive', 'string', ['string']);
+    lspSendReceive = function (input: String, callbacks) {
+      // We are reusing the `runWithCallbacks` function that was supposed to
+      // only receive _solidity_compile as second parameter.
+      // I may be wrong, but that should work analogous.
+      return runWithCallbacks(callbacks, wrappedLspSendReceive, [input]);
+    };
+  }
+
   // This calls compile() with args || cb
   const runWithCallbacks = function (callbacks, compile, args) {
     if (callbacks) {
@@ -324,6 +343,8 @@ function setupMethods (soljson) {
       importCallback: compileJSONCallback !== null || compileStandard !== null,
       nativeStandardJSON: compileStandard !== null
     },
+    lspStart: lspStart,
+    lspSendReceive: lspSendReceive,
     compile: compileStandardWrapper,
     // Loads the compiler of the given version from the github repository
     // instead of from the local filesystem.