From 94b912b649150b9863a62096ba4740b2cc8ad21a Mon Sep 17 00:00:00 2001
From: Elizabeth Alexander Hunt <me@liz.coffee>
Date: Sun, 5 Jul 2026 12:42:44 -0700
Subject: Factor

---
 src/toys/turing/js/parser.js | 141 -------------------------------------------
 1 file changed, 141 deletions(-)
 delete mode 100644 src/toys/turing/js/parser.js

(limited to 'src/toys/turing/js/parser.js')

diff --git a/src/toys/turing/js/parser.js b/src/toys/turing/js/parser.js
deleted file mode 100644
index dd65613..0000000
--- a/src/toys/turing/js/parser.js
+++ /dev/null
@@ -1,141 +0,0 @@
-export function parseInstructionSet(code) {
-  const lines = code.split("\n");
-  const instructions = [];
-  const config = {
-    startState: null,
-    acceptStates: new Set(),
-    rejectStates: new Set()
-  };
-
-  lines.forEach((line, lineIndex) => {
-    const withoutComments = line.replace(/\/\/.*$/, "").trim();
-    if (!withoutComments) {
-      return;
-    }
-
-    if (withoutComments.startsWith("#")) {
-      applyDirective(withoutComments.slice(1).trim(), config, lineIndex + 1);
-      return;
-    }
-
-    const parts = withoutComments.split(/\s+/).filter(Boolean);
-    if (parts.length !== 5) {
-      throw new Error(`Invalid instruction on line ${lineIndex + 1}: expected 5 parts, received ${parts.length}`);
-    }
-
-    const [fromState, readSymbol, writeSymbol, direction, toState] = parts;
-    if (!config.startState) {
-      config.startState = fromState;
-    }
-
-    instructions.push({ fromState, readSymbol, writeSymbol, direction, toState, line: lineIndex + 1 });
-  });
-
-  if (!instructions.length) {
-    throw new Error("No instructions provided");
-  }
-
-  const { acceptStates, rejectStates } = deriveHaltingStates(instructions, config);
-  const rules = buildRuleMap(instructions);
-
-  return {
-    rules,
-    startState: config.startState ?? instructions[0].fromState,
-    acceptStates,
-    rejectStates
-  };
-}
-
-function applyDirective(directiveLine, config, lineNumber) {
-  if (!directiveLine) {
-    return;
-  }
-
-  const [keyword, ...values] = directiveLine.split(/\s+/).filter(Boolean);
-  if (!keyword) {
-    return;
-  }
-
-  switch (keyword.toLowerCase()) {
-    case "start": {
-      if (values.length !== 1) {
-        throw new Error(`#start on line ${lineNumber} must provide exactly one state`);
-      }
-      config.startState = values[0];
-      break;
-    }
-    case "accept":
-    case "accepts":
-    case "accepting": {
-      if (!values.length) {
-        throw new Error(`#${keyword} on line ${lineNumber} must include at least one state`);
-      }
-      values.forEach((value) => config.acceptStates.add(value));
-      break;
-    }
-    case "reject":
-    case "rejects":
-    case "rejecting": {
-      if (!values.length) {
-        throw new Error(`#${keyword} on line ${lineNumber} must include at least one state`);
-      }
-      values.forEach((value) => config.rejectStates.add(value));
-      break;
-    }
-    default:
-      throw new Error(`Unknown directive '#${keyword}' on line ${lineNumber}`);
-  }
-}
-
-function deriveHaltingStates(instructions, config) {
-  const fromStates = new Set();
-  const toStates = new Set();
-  const allStates = new Set();
-
-  instructions.forEach(({ fromState, toState }) => {
-    fromStates.add(fromState);
-    toStates.add(toState);
-    allStates.add(fromState);
-    allStates.add(toState);
-  });
-
-  // Remove any overlap so rejects always win
-  config.rejectStates.forEach((state) => config.acceptStates.delete(state));
-
-  if (!config.acceptStates.size) {
-    for (const state of allStates) {
-      if (!fromStates.has(state) && toStates.has(state) && !config.rejectStates.has(state)) {
-        config.acceptStates.add(state);
-      }
-    }
-  }
-
-  return {
-    acceptStates: Array.from(config.acceptStates),
-    rejectStates: Array.from(config.rejectStates)
-  };
-}
-
-function buildRuleMap(instructions) {
-  const rules = new Map();
-
-  instructions.forEach(({ fromState, readSymbol, writeSymbol, direction, toState, line }) => {
-    const dir = direction.toUpperCase();
-    if (!["L", "R", "S"].includes(dir)) {
-      throw new Error(`Invalid direction '${direction}' on line ${line}. Use L, R, or S.`);
-    }
-
-    const key = `${fromState}:${readSymbol}`;
-    if (rules.has(key)) {
-      throw new Error(`Duplicate rule for state '${fromState}' reading '${readSymbol}' (line ${line})`);
-    }
-
-    rules.set(key, {
-      nextState: toState,
-      writeSymbol,
-      direction: dir
-    });
-  });
-
-  return rules;
-}
-- 
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