Initial bits for integrating the LSP API.

Author: christianparpart

README.md

@@ -204,6 +204,51 @@ 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 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.
+solc.lspStart(fileReadCallback);
+
+// Send some LSP JSON-RPC message and optionally receive a reply.
+var lspMessage = {
+	'rootUri': 'file:///project/',
+	'capabilities': {
+		'textDocument': {
+			'publishDiagnostics': {'relatedInformation': true}
+		},
+		'workspace': {
+			'applyEdit': true,
+			'configuration': true,
+			'didChangeConfiguration': {'dynamicRegistration': true},
+			'workspaceEdit': {'documentChanges': true},
+			'workspaceFolders': true
+		}
+	}
+};
+var lspReply = JSON.parse(solc.lspSendReceive(JSON.stringify(lspMessage)));
+```
+
 ### Using with Electron
 
 **Note:**

wrapper.ts

@@ -92,6 +92,25 @@ function setupMethods (soljson) {
     };
   };
 
+  let lspStart = null;
+  if ('_solidity_lsp_start' in soljson) {
+    let wrappedLspStart = soljson.cwrap('solidity_lsp_start', 'int', []);
+    lspStart = function (callbacks) {
+      return runWithCallbacks(callbacks, wrappedLspStart, []);
+    };
+  }
+
+  let lspSendReceive = null;
+  if ('_solidity_lsp_send_receive' in soljson) {
+    let 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.