very basic parser works

2025-03-15 07:28:55 +00:00 · 2022-04-06 21:59:55 +02:00 · 2022-04-06 21:59:55 +02:00 · e5679c765d
commit e5679c765d
parent 542dc86188
2 changed files with 149 additions and 0 deletions
--- a/interpreter-test.html
+++ b/interpreter-test.html
@ -0,0 +1,6 @@
+<!DOCTYPE html>
+<html>
+	<head>
+		<script type="text/javascript" src="interpreter.js"></script>
+	</head>
+</html>
--- a/interpreter.js
+++ b/interpreter.js
@ -0,0 +1,143 @@
+"use strict";
+(function(){
+	var variables = [];
+	var functions = [];
+	var file = "[anonymous]";
+
+
+	function executeCommand(args, std) {
+		console.log(args, std);
+	}
+
+	function astSequence() {
+		let commands = [];
+		return {
+			add: c => commands.push(c),
+			execute: (std) => commands.forEach(c => c.execute(std)),
+		}
+	}
+
+	function astCommand() {
+		let args = [];
+		return {
+			add: a => args.push(a),
+			execute: (std) => {
+				let evaluatedArgs = args.map(a => a.evaluate());
+				executeCommand(evaluatedArgs, std);
+			},
+		};
+	}
+
+	function astValueCompound() {
+		let components = [];
+		return {
+			add: c => components.push(c),
+			evaluate: () => components.map(c => c.evaluate()).join(""),
+		};
+	}
+
+	function astValueString(str) {
+		return {
+			evaluate: () => str,
+		};
+	}
+
+	function astValueVar(name) {
+		return {
+			// add support for multiple arguments in one variable
+			evaluate: () => variables[name],
+		}
+	}
+
+	function astValueCommandSubstitution(ast) {
+		return {
+			evaluate: () => {
+				// TODO
+			},
+		};
+	}
+
+	function astValueProcessSubstitution(ast) {
+		return {
+			evaluate: () => {
+				// TODO
+			},
+		};
+	}
+
+	function panic(line, message) {
+		throw `${file}: line ${line}: panic: ${message}`;
+	}
+
+	function syntaxError(line, message) {
+		throw `${file}: line ${line}: syntax error: ${message}`;
+	}
+
+	function parseCommands(content) {
+		let line = 1;
+
+		const PS_INIT    = 0;
+		const PS_COMMENT = -1;
+		const PS_COMMAND = 1;
+
+		let astRoot = astSequence();
+		let current = null;
+
+		let state = PS_INIT;
+		let buffer = "";
+
+		const length = content.length;
+		for (let i = 0; i < length; i++) {
+			const c = content[i];
+			switch(state) {
+				case PS_INIT:
+					if (['\n', '\r', ' ', '\t', ';'].includes(c)) {
+						// continue
+					} else if (c == '#') {
+						state = PS_COMMENT;
+					} else {
+						current = astCommand();
+						buffer = c;
+						state = PS_COMMAND;
+					}
+					break;
+				case PS_COMMENT:
+					if (c == '\n') {
+						state = PS_INIT;
+					}
+					break;
+				case PS_COMMAND:
+					// check for escape and quotes
+					if (c == ';' || c == '\n') {
+						if (buffer) {
+							current.add(astValueString(buffer));
+							buffer = "";
+						}
+						astRoot.add(current);
+						current = null;
+						state = PS_INIT;
+					} else if (c == ' ' || c == '\t') {
+						if (buffer) {
+							current.add(astValueString(buffer));
+							buffer = "";
+						}
+					} else {
+						buffer += c;
+					}
+					break;
+				default:
+					panic(line, "unknown parse state");
+					break;
+			}
+			if (c == '\n') {
+				line++;
+			}
+		}
+
+		return astRoot;
+	}
+
+	window.sh = {
+		parse: parseCommands,
+	};
+})();