neo-decompiler 0.11.0

import {
  containsIdentifier,
  isTempIdent,
  parseAssignment,
  replaceIdentifier,
  TEMP_TOKEN_RE,
} from "./postprocess-shared.js";

function isSafeToInline(expr) {
  if (expr.includes("(")) {
    const trimmed = expr.trim();
    if (trimmed.startsWith("(") && trimmed.endsWith(")")) return true;
    return false;
  }
  return true;
}

function needsParens(expr) {
  // Check for operator characters outside of string literals and bracket indexing.
  let depth = 0;
  let inString = false;
  let quote = "";
  for (let i = 0; i < expr.length; i++) {
    const ch = expr[i];
    if (inString) {
      if (ch === "\\" && i + 1 < expr.length) {
        i++;
      } else if (ch === quote) {
        inString = false;
      }
      continue;
    }
    if (ch === '"' || ch === "'") {
      inString = true;
      quote = ch;
      continue;
    }
    if (ch === "[" || ch === "(") {
      depth++;
      continue;
    }
    if (ch === "]" || ch === ")") {
      depth--;
      continue;
    }
    if (depth > 0) continue;
    if (
      ch === "+" ||
      ch === "-" ||
      ch === "*" ||
      ch === "/" ||
      ch === "%" ||
      ch === "<" ||
      ch === ">"
    ) {
      return true;
    }
    if (ch === "&" && i + 1 < expr.length && expr[i + 1] === "&") return true;
    if (ch === "|" && i + 1 < expr.length && expr[i + 1] === "|") return true;
    if (ch === "=" && i + 1 < expr.length && expr[i + 1] === "=") return true;
    if (ch === "!" && i + 1 < expr.length && expr[i + 1] === "=") return true;
  }
  return false;
}

function isControlFlowCondition(statement) {
  const t = statement.trim();
  return (
    t.startsWith("if ") ||
    t.startsWith("while ") ||
    t.startsWith("for ") ||
    t.startsWith("} else if ")
  );
}

function isNumericLiteral(text) {
  const t = text.startsWith("-") ? text.slice(1) : text;
  if (t.startsWith("0x") || t.startsWith("0X")) {
    const hex = t.slice(2);
    return hex.length > 0 && /^[0-9a-fA-F]+$/.test(hex);
  }
  return t.length > 0 && /^\d+$/.test(t);
}

function isStringLiteral(text) {
  if (text.length < 2) return false;
  return (
    (text[0] === '"' && text[text.length - 1] === '"') ||
    (text[0] === "'" && text[text.length - 1] === "'")
  );
}

function isSimpleIdentifier(text) {
  if (text.length === 0) return false;
  if (!/^[A-Za-z_]/.test(text)) return false;
  return /^\w+$/.test(text);
}

function isTrivialInlineRhs(expr) {
  const t = expr.trim();
  if (t === "") return false;
  if (t === "true" || t === "false" || t === "null") return true;
  if (isNumericLiteral(t) || isStringLiteral(t)) return true;
  return isSimpleIdentifier(t);
}

function collectInlineCandidates(statements) {
  const definitions = new Map();
  const useCounts = new Map();
  const reassigned = new Set();
  const known = new Set();

  for (let idx = 0; idx < statements.length; idx++) {
    const trimmed = statements[idx].trim();
    const assign = parseAssignment(trimmed);
    const scanText = assign ? assign.rhs : trimmed;

    if (known.size > 0 && scanText !== "") {
      const matches = scanText.match(TEMP_TOKEN_RE);
      if (matches !== null) {
        for (let m = 0; m < matches.length; m++) {
          const v = matches[m];
          if (known.has(v)) {
            useCounts.set(v, (useCounts.get(v) || 0) + 1);
          }
        }
      }
    }

    if (assign) {
      if (!isTempIdent(assign.lhs)) continue;

      if (assign.hasLet) {
        if (definitions.has(assign.lhs)) {
          reassigned.add(assign.lhs);
        } else {
          known.add(assign.lhs);
          definitions.set(assign.lhs, { defLine: idx, rhs: assign.rhs });
        }
      } else {
        reassigned.add(assign.lhs);
      }
    }
  }

  const candidates = [];
  for (const [name, { defLine, rhs }] of definitions) {
    const count = useCounts.get(name) || 0;
    if (count === 1 && !reassigned.has(name) && isSafeToInline(rhs)) {
      candidates.push({ name, defLine, rhs });
    }
  }

  candidates.sort((a, b) => b.defLine - a.defLine);
  return candidates;
}

function applyInlining(statements, candidates) {
  for (const candidate of candidates) {
    let inlined = false;
    for (let i = candidate.defLine + 1; i < statements.length; i++) {
      if (!containsIdentifier(statements[i], candidate.name)) continue;

      if (
        isControlFlowCondition(statements[i]) &&
        !isTrivialInlineRhs(candidate.rhs)
      ) {
        break;
      }

      const replacement = needsParens(candidate.rhs)
        ? `(${candidate.rhs})`
        : candidate.rhs;

      const updated = replaceIdentifier(
        statements[i],
        candidate.name,
        replacement,
      );
      if (updated !== statements[i]) {
        statements[i] = updated;
        inlined = true;
        break;
      }
    }

    if (inlined) {
      statements[candidate.defLine] = "";
    }
  }
}

export function inlineSingleUseTemps(statements) {
  const candidates = collectInlineCandidates(statements);
  applyInlining(statements, candidates);
}