parser.ts

import { CharStream, CommonTokenStream } from 'antlr4'

import SolidityLexer from './antlr/SolidityLexer'
import SolidityParser from './antlr/SolidityParser'
import {
  ASTNode,
  astNodeTypes,
  ASTNodeTypeString,
  ASTVisitor,
  SourceUnit,
} from './ast-types'
import { ASTBuilder } from './ASTBuilder'
import ErrorListener from './ErrorListener'
import { buildCommentList, buildTokenList } from './tokens'
import { ParseOptions, Token, TokenizeOptions } from './types'

interface ParserErrorItem {
  message: string
  line: number
  column: number
}

type ParseResult = SourceUnit & {
  errors?: any[]
  tokens?: Token[]
}

export class ParserError extends Error {
  public errors: ParserErrorItem[]

  constructor(args: { errors: ParserErrorItem[] }) {
    super()
    const { message, line, column } = args.errors[0]
    this.message = `${message} (${line}:${column})`
    this.errors = args.errors

    if (Error.captureStackTrace !== undefined) {
      Error.captureStackTrace(this, this.constructor)
    } else {
      this.stack = new Error().stack
    }
  }
}

export function tokenize(input: string, options: TokenizeOptions = {}): any {
  const inputStream = new CharStream(input)
  const lexer = new SolidityLexer(inputStream)

  return buildTokenList(lexer.getAllTokens(), options)
}

export function parse(input: string, options: ParseOptions = {}): ParseResult {
  const inputStream = new CharStream(input)
  const lexer = new SolidityLexer(inputStream)
  const tokenStream = new CommonTokenStream(lexer)
  const parser = new SolidityParser(tokenStream)

  const listener = new ErrorListener()
  lexer.removeErrorListeners()
  lexer.addErrorListener(listener)

  parser.removeErrorListeners()
  parser.addErrorListener(listener)
  parser.buildParseTrees = true

  const sourceUnit = parser.sourceUnit()

  const astBuilder = new ASTBuilder(options)

  astBuilder.visit(sourceUnit)

  const ast: ParseResult | null = astBuilder.result

  if (ast === null) {
    throw new Error('ast should never be null')
  }

  if (options.tokens === true) {
    ast.tokens = buildTokenList(tokenStream.tokens, options)
  }

  if (options.comments === true) {
    ast.comments = buildCommentList(
      tokenStream.tokens,
      lexer.channelNames.indexOf('HIDDEN'),
      options
    )
  }

  if (listener.hasErrors()) {
    if (options.tolerant !== true) {
      throw new ParserError({ errors: listener.getErrors() })
    }
    ast.errors = listener.getErrors()
  }

  return ast
}

function _isASTNode(node: unknown): node is ASTNode {
  if (typeof node !== 'object' || node === null) {
    return false
  }

  const nodeAsASTNode = node as ASTNode

  if (
    Object.prototype.hasOwnProperty.call(nodeAsASTNode, 'type') &&
    typeof nodeAsASTNode.type === 'string'
  ) {
    return astNodeTypes.includes(nodeAsASTNode.type)
  }

  return false
}

export function visit(
  node: unknown,
  visitor: ASTVisitor,
  nodeParent?: ASTNode
): void {
  if (Array.isArray(node)) {
    node.forEach((child) => visit(child, visitor, nodeParent))
  }

  if (!_isASTNode(node)) return

  let cont = true

  if (visitor[node.type] !== undefined) {
    // TODO can we avoid this `as never`
    cont = visitor[node.type]!(node as never, nodeParent)
  }

  if (cont === false) return

  for (const prop in node) {
    if (Object.prototype.hasOwnProperty.call(node, prop)) {
      // TODO can we avoid this `as any`
      visit((node as any)[prop], visitor, node)
    }
  }

  const selector = (node.type + ':exit') as `${ASTNodeTypeString}:exit`
  if (visitor[selector] !== undefined) {
    // TODO can we avoid this `as never`
    visitor[selector]!(node as never, nodeParent)
  }
}