From 0add2510d68f103870aa39588f0ae75f82250882 Mon Sep 17 00:00:00 2001
From: Alberto Lerda <alberto@dyne.org>
Date: Fri, 29 Sep 2023 10:44:06 +0100
Subject: [PATCH] ethereum connect

For the moment I am using one file for each verb (e.g. read.ts and connect.ts).
The result is that connect is a parser that matches only one sentence.
---
 pkg/ethereum/src/connect.ts | 96 +++++++++++++++++++++++++++++++++++++
 pkg/ethereum/test/read.ts   |  7 ++-
 2 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 pkg/ethereum/src/connect.ts

diff --git a/pkg/ethereum/src/connect.ts b/pkg/ethereum/src/connect.ts
new file mode 100644
index 00000000..ba8c2da7
--- /dev/null
+++ b/pkg/ethereum/src/connect.ts
@@ -0,0 +1,96 @@
+import { createToken, Lexer, CstParser } from "@slangroom/deps/chevrotain";
+import { JsonableObject } from "@slangroom/shared";
+import { StmtContext } from "@slangroom/core/slangroom";
+import { Whitespace, Identifier } from "@slangroom/shared/tokens"
+import { Web3 } from 'web3'
+
+type EthereumConnect = {
+	address: string
+}
+
+const Ethereum = createToken({
+	name: "Ethereum",
+	pattern: /ethereum/i,
+});
+const The = createToken({
+	name: "The",
+	pattern: /the/i,
+	group: Lexer.SKIPPED,
+});
+const Provider = createToken({
+	name: "Provider",
+	pattern: /Provider/i,
+});
+const To = createToken({
+	name: "To",
+	pattern: /To/i,
+});
+
+const allTokens = [
+	Whitespace,
+	The,
+	To,
+	Ethereum,
+	Provider,
+	Identifier,
+];
+const StatementLexer = new Lexer(allTokens);
+// ----------------- parser -----------------
+class StatementParser extends CstParser {
+	constructor() {
+		super(allTokens);
+
+		this.performSelfAnalysis();
+	}
+
+	public statement = this.RULE("statement", () => {
+		this.CONSUME(To);
+		this.CONSUME(Ethereum);
+		this.CONSUME(Provider);
+		this.CONSUME(Identifier);
+	});
+}
+
+const parser = new StatementParser();
+// ----------------- Interpreter -----------------
+const BaseCstVisitor = parser.getBaseCstVisitorConstructor();
+
+class StatementInterpreter extends BaseCstVisitor {
+	constructor() {
+		super();
+		this.validateVisitor();
+	}
+	statement(ctx: any) {
+		return {address: ctx.Identifier[0].image.slice(1,-1)}
+	}
+}
+
+// We only need a single interpreter instance because our interpreter has no state.
+const interpreter = new StatementInterpreter();
+
+
+export const line2Ast = (text: string) => {
+	const lexResult = StatementLexer.tokenize(text);
+	parser.input = lexResult.tokens;
+	const cst = parser.statement();
+	const value = interpreter.visit(cst);
+	return {
+		value: value,
+		lexResult: lexResult,
+		parseErrors: parser.errors,
+	};
+}
+
+type EthereumConnectResult = {
+	name: string,
+	value: Web3
+}
+
+export const evaluate = async (ast: EthereumConnect,
+                keys: JsonableObject, stmtCtx: StmtContext): Promise<EthereumConnectResult> => {
+	const address = (keys[ast.address] || stmtCtx.data[ast.address] || ast.address) as string
+	return {
+		name: "web3",
+		value: new Web3(address)
+	}
+}
diff --git a/pkg/ethereum/test/read.ts b/pkg/ethereum/test/read.ts
index 002f7fa6..6c688b92 100644
--- a/pkg/ethereum/test/read.ts
+++ b/pkg/ethereum/test/read.ts
@@ -4,9 +4,14 @@ import { Web3 } from 'web3'
 const test = anyTest as TestFn<{web3: Web3}>;
 
 import { EthereumRequestKind, line2Ast, evaluate } from '@slangroom/ethereum/read';
+import { line2Ast as line2AstConnect, evaluate as evaluateConnect } from '@slangroom/ethereum/connect';
 
 test.before(async (t) => {
-	t.context.web3 = new Web3('http://78.47.38.223:9485')
+	const ast = line2AstConnect("to the ethereum provider 'foo'");
+	t.deepEqual(ast.value, { address: 'foo' })
+	const res = await evaluateConnect(ast.value, {}, {data: {foo: "http://78.47.38.223:9485"}, context: t.context})
+	t.is(res.name, "web3")
+	t.context.web3 = res.value
 });
 
 test("Ethereum nonce", async (t) => {