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node_modules/graphql/language/lexer.js.flow

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+// @flow strict
+
+import defineToJSON from '../jsutils/defineToJSON';
+
+import { syntaxError } from '../error/syntaxError';
+
+import { type Token } from './ast';
+import { type Source } from './source';
+import { dedentBlockStringValue } from './blockString';
+import { type TokenKindEnum, TokenKind } from './tokenKind';
+
+/**
+ * Given a Source object, this returns a Lexer for that source.
+ * A Lexer is a stateful stream generator in that every time
+ * it is advanced, it returns the next token in the Source. Assuming the
+ * source lexes, the final Token emitted by the lexer will be of kind
+ * EOF, after which the lexer will repeatedly return the same EOF token
+ * whenever called.
+ */
+export function createLexer<TOptions>(
+  source: Source,
+  options: TOptions,
+): Lexer<TOptions> {
+  const startOfFileToken = new Tok(TokenKind.SOF, 0, 0, 0, 0, null);
+  const lexer: Lexer<TOptions> = {
+    source,
+    options,
+    lastToken: startOfFileToken,
+    token: startOfFileToken,
+    line: 1,
+    lineStart: 0,
+    advance: advanceLexer,
+    lookahead,
+  };
+  return lexer;
+}
+
+function advanceLexer() {
+  this.lastToken = this.token;
+  const token = (this.token = this.lookahead());
+  return token;
+}
+
+function lookahead() {
+  let token = this.token;
+  if (token.kind !== TokenKind.EOF) {
+    do {
+      // Note: next is only mutable during parsing, so we cast to allow this.
+      token = token.next || ((token: any).next = readToken(this, token));
+    } while (token.kind === TokenKind.COMMENT);
+  }
+  return token;
+}
+
+/**
+ * The return type of createLexer.
+ */
+export type Lexer<TOptions> = {
+  source: Source,
+  options: TOptions,
+
+  /**
+   * The previously focused non-ignored token.
+   */
+  lastToken: Token,
+
+  /**
+   * The currently focused non-ignored token.
+   */
+  token: Token,
+
+  /**
+   * The (1-indexed) line containing the current token.
+   */
+  line: number,
+
+  /**
+   * The character offset at which the current line begins.
+   */
+  lineStart: number,
+
+  /**
+   * Advances the token stream to the next non-ignored token.
+   */
+  advance(): Token,
+
+  /**
+   * Looks ahead and returns the next non-ignored token, but does not change
+   * the Lexer's state.
+   */
+  lookahead(): Token,
+
+  ...
+};
+
+// @internal
+export function isPunctuatorToken(token: Token) {
+  const kind = token.kind;
+  return (
+    kind === TokenKind.BANG ||
+    kind === TokenKind.DOLLAR ||
+    kind === TokenKind.AMP ||
+    kind === TokenKind.PAREN_L ||
+    kind === TokenKind.PAREN_R ||
+    kind === TokenKind.SPREAD ||
+    kind === TokenKind.COLON ||
+    kind === TokenKind.EQUALS ||
+    kind === TokenKind.AT ||
+    kind === TokenKind.BRACKET_L ||
+    kind === TokenKind.BRACKET_R ||
+    kind === TokenKind.BRACE_L ||
+    kind === TokenKind.PIPE ||
+    kind === TokenKind.BRACE_R
+  );
+}
+
+/**
+ * Helper function for constructing the Token object.
+ */
+function Tok(
+  kind: TokenKindEnum,
+  start: number,
+  end: number,
+  line: number,
+  column: number,
+  prev: Token | null,
+  value?: string,
+) {
+  this.kind = kind;
+  this.start = start;
+  this.end = end;
+  this.line = line;
+  this.column = column;
+  this.value = value;
+  this.prev = prev;
+  this.next = null;
+}
+
+// Print a simplified form when appearing in JSON/util.inspect.
+defineToJSON(Tok, function() {
+  return {
+    kind: this.kind,
+    value: this.value,
+    line: this.line,
+    column: this.column,
+  };
+});
+
+function printCharCode(code) {
+  return (
+    // NaN/undefined represents access beyond the end of the file.
+    isNaN(code)
+      ? TokenKind.EOF
+      : // Trust JSON for ASCII.
+      code < 0x007f
+      ? JSON.stringify(String.fromCharCode(code))
+      : // Otherwise print the escaped form.
+        `"\\u${('00' + code.toString(16).toUpperCase()).slice(-4)}"`
+  );
+}
+
+/**
+ * Gets the next token from the source starting at the given position.
+ *
+ * This skips over whitespace until it finds the next lexable token, then lexes
+ * punctuators immediately or calls the appropriate helper function for more
+ * complicated tokens.
+ */
+function readToken(lexer: Lexer<mixed>, prev: Token): Token {
+  const source = lexer.source;
+  const body = source.body;
+  const bodyLength = body.length;
+
+  const pos = positionAfterWhitespace(body, prev.end, lexer);
+  const line = lexer.line;
+  const col = 1 + pos - lexer.lineStart;
+
+  if (pos >= bodyLength) {
+    return new Tok(TokenKind.EOF, bodyLength, bodyLength, line, col, prev);
+  }
+
+  const code = body.charCodeAt(pos);
+
+  // SourceCharacter
+  switch (code) {
+    // !
+    case 33:
+      return new Tok(TokenKind.BANG, pos, pos + 1, line, col, prev);
+    // #
+    case 35:
+      return readComment(source, pos, line, col, prev);
+    // $
+    case 36:
+      return new Tok(TokenKind.DOLLAR, pos, pos + 1, line, col, prev);
+    // &
+    case 38:
+      return new Tok(TokenKind.AMP, pos, pos + 1, line, col, prev);
+    // (
+    case 40:
+      return new Tok(TokenKind.PAREN_L, pos, pos + 1, line, col, prev);
+    // )
+    case 41:
+      return new Tok(TokenKind.PAREN_R, pos, pos + 1, line, col, prev);
+    // .
+    case 46:
+      if (body.charCodeAt(pos + 1) === 46 && body.charCodeAt(pos + 2) === 46) {
+        return new Tok(TokenKind.SPREAD, pos, pos + 3, line, col, prev);
+      }
+      break;
+    // :
+    case 58:
+      return new Tok(TokenKind.COLON, pos, pos + 1, line, col, prev);
+    // =
+    case 61:
+      return new Tok(TokenKind.EQUALS, pos, pos + 1, line, col, prev);
+    // @
+    case 64:
+      return new Tok(TokenKind.AT, pos, pos + 1, line, col, prev);
+    // [
+    case 91:
+      return new Tok(TokenKind.BRACKET_L, pos, pos + 1, line, col, prev);
+    // ]
+    case 93:
+      return new Tok(TokenKind.BRACKET_R, pos, pos + 1, line, col, prev);
+    // {
+    case 123:
+      return new Tok(TokenKind.BRACE_L, pos, pos + 1, line, col, prev);
+    // |
+    case 124:
+      return new Tok(TokenKind.PIPE, pos, pos + 1, line, col, prev);
+    // }
+    case 125:
+      return new Tok(TokenKind.BRACE_R, pos, pos + 1, line, col, prev);
+    // A-Z _ a-z
+    case 65:
+    case 66:
+    case 67:
+    case 68:
+    case 69:
+    case 70:
+    case 71:
+    case 72:
+    case 73:
+    case 74:
+    case 75:
+    case 76:
+    case 77:
+    case 78:
+    case 79:
+    case 80:
+    case 81:
+    case 82:
+    case 83:
+    case 84:
+    case 85:
+    case 86:
+    case 87:
+    case 88:
+    case 89:
+    case 90:
+    case 95:
+    case 97:
+    case 98:
+    case 99:
+    case 100:
+    case 101:
+    case 102:
+    case 103:
+    case 104:
+    case 105:
+    case 106:
+    case 107:
+    case 108:
+    case 109:
+    case 110:
+    case 111:
+    case 112:
+    case 113:
+    case 114:
+    case 115:
+    case 116:
+    case 117:
+    case 118:
+    case 119:
+    case 120:
+    case 121:
+    case 122:
+      return readName(source, pos, line, col, prev);
+    // - 0-9
+    case 45:
+    case 48:
+    case 49:
+    case 50:
+    case 51:
+    case 52:
+    case 53:
+    case 54:
+    case 55:
+    case 56:
+    case 57:
+      return readNumber(source, pos, code, line, col, prev);
+    // "
+    case 34:
+      if (body.charCodeAt(pos + 1) === 34 && body.charCodeAt(pos + 2) === 34) {
+        return readBlockString(source, pos, line, col, prev, lexer);
+      }
+      return readString(source, pos, line, col, prev);
+  }
+
+  throw syntaxError(source, pos, unexpectedCharacterMessage(code));
+}
+
+/**
+ * Report a message that an unexpected character was encountered.
+ */
+function unexpectedCharacterMessage(code) {
+  if (code < 0x0020 && code !== 0x0009 && code !== 0x000a && code !== 0x000d) {
+    return `Cannot contain the invalid character ${printCharCode(code)}.`;
+  }
+
+  if (code === 39) {
+    // '
+    return 'Unexpected single quote character (\'), did you mean to use a double quote (")?';
+  }
+
+  return `Cannot parse the unexpected character ${printCharCode(code)}.`;
+}
+
+/**
+ * Reads from body starting at startPosition until it finds a non-whitespace
+ * character, then returns the position of that character for lexing.
+ */
+function positionAfterWhitespace(
+  body: string,
+  startPosition: number,
+  lexer: Lexer<mixed>,
+): number {
+  const bodyLength = body.length;
+  let position = startPosition;
+  while (position < bodyLength) {
+    const code = body.charCodeAt(position);
+    // tab | space | comma | BOM
+    if (code === 9 || code === 32 || code === 44 || code === 0xfeff) {
+      ++position;
+    } else if (code === 10) {
+      // new line
+      ++position;
+      ++lexer.line;
+      lexer.lineStart = position;
+    } else if (code === 13) {
+      // carriage return
+      if (body.charCodeAt(position + 1) === 10) {
+        position += 2;
+      } else {
+        ++position;
+      }
+      ++lexer.line;
+      lexer.lineStart = position;
+    } else {
+      break;
+    }
+  }
+  return position;
+}
+
+/**
+ * Reads a comment token from the source file.
+ *
+ * #[\u0009\u0020-\uFFFF]*
+ */
+function readComment(source, start, line, col, prev): Token {
+  const body = source.body;
+  let code;
+  let position = start;
+
+  do {
+    code = body.charCodeAt(++position);
+  } while (
+    !isNaN(code) &&
+    // SourceCharacter but not LineTerminator
+    (code > 0x001f || code === 0x0009)
+  );
+
+  return new Tok(
+    TokenKind.COMMENT,
+    start,
+    position,
+    line,
+    col,
+    prev,
+    body.slice(start + 1, position),
+  );
+}
+
+/**
+ * Reads a number token from the source file, either a float
+ * or an int depending on whether a decimal point appears.
+ *
+ * Int:   -?(0|[1-9][0-9]*)
+ * Float: -?(0|[1-9][0-9]*)(\.[0-9]+)?((E|e)(+|-)?[0-9]+)?
+ */
+function readNumber(source, start, firstCode, line, col, prev): Token {
+  const body = source.body;
+  let code = firstCode;
+  let position = start;
+  let isFloat = false;
+
+  if (code === 45) {
+    // -
+    code = body.charCodeAt(++position);
+  }
+
+  if (code === 48) {
+    // 0
+    code = body.charCodeAt(++position);
+    if (code >= 48 && code <= 57) {
+      throw syntaxError(
+        source,
+        position,
+        `Invalid number, unexpected digit after 0: ${printCharCode(code)}.`,
+      );
+    }
+  } else {
+    position = readDigits(source, position, code);
+    code = body.charCodeAt(position);
+  }
+
+  if (code === 46) {
+    // .
+    isFloat = true;
+
+    code = body.charCodeAt(++position);
+    position = readDigits(source, position, code);
+    code = body.charCodeAt(position);
+  }
+
+  if (code === 69 || code === 101) {
+    // E e
+    isFloat = true;
+
+    code = body.charCodeAt(++position);
+    if (code === 43 || code === 45) {
+      // + -
+      code = body.charCodeAt(++position);
+    }
+    position = readDigits(source, position, code);
+    code = body.charCodeAt(position);
+  }
+
+  // Numbers cannot be followed by . or e
+  if (code === 46 || code === 69 || code === 101) {
+    throw syntaxError(
+      source,
+      position,
+      `Invalid number, expected digit but got: ${printCharCode(code)}.`,
+    );
+  }
+
+  return new Tok(
+    isFloat ? TokenKind.FLOAT : TokenKind.INT,
+    start,
+    position,
+    line,
+    col,
+    prev,
+    body.slice(start, position),
+  );
+}
+
+/**
+ * Returns the new position in the source after reading digits.
+ */
+function readDigits(source, start, firstCode) {
+  const body = source.body;
+  let position = start;
+  let code = firstCode;
+  if (code >= 48 && code <= 57) {
+    // 0 - 9
+    do {
+      code = body.charCodeAt(++position);
+    } while (code >= 48 && code <= 57); // 0 - 9
+    return position;
+  }
+  throw syntaxError(
+    source,
+    position,
+    `Invalid number, expected digit but got: ${printCharCode(code)}.`,
+  );
+}
+
+/**
+ * Reads a string token from the source file.
+ *
+ * "([^"\\\u000A\u000D]|(\\(u[0-9a-fA-F]{4}|["\\/bfnrt])))*"
+ */
+function readString(source, start, line, col, prev): Token {
+  const body = source.body;
+  let position = start + 1;
+  let chunkStart = position;
+  let code = 0;
+  let value = '';
+
+  while (
+    position < body.length &&
+    !isNaN((code = body.charCodeAt(position))) &&
+    // not LineTerminator
+    code !== 0x000a &&
+    code !== 0x000d
+  ) {
+    // Closing Quote (")
+    if (code === 34) {
+      value += body.slice(chunkStart, position);
+      return new Tok(
+        TokenKind.STRING,
+        start,
+        position + 1,
+        line,
+        col,
+        prev,
+        value,
+      );
+    }
+
+    // SourceCharacter
+    if (code < 0x0020 && code !== 0x0009) {
+      throw syntaxError(
+        source,
+        position,
+        `Invalid character within String: ${printCharCode(code)}.`,
+      );
+    }
+
+    ++position;
+    if (code === 92) {
+      // \
+      value += body.slice(chunkStart, position - 1);
+      code = body.charCodeAt(position);
+      switch (code) {
+        case 34:
+          value += '"';
+          break;
+        case 47:
+          value += '/';
+          break;
+        case 92:
+          value += '\\';
+          break;
+        case 98:
+          value += '\b';
+          break;
+        case 102:
+          value += '\f';
+          break;
+        case 110:
+          value += '\n';
+          break;
+        case 114:
+          value += '\r';
+          break;
+        case 116:
+          value += '\t';
+          break;
+        case 117: {
+          // uXXXX
+          const charCode = uniCharCode(
+            body.charCodeAt(position + 1),
+            body.charCodeAt(position + 2),
+            body.charCodeAt(position + 3),
+            body.charCodeAt(position + 4),
+          );
+          if (charCode < 0) {
+            const invalidSequence = body.slice(position + 1, position + 5);
+            throw syntaxError(
+              source,
+              position,
+              `Invalid character escape sequence: \\u${invalidSequence}.`,
+            );
+          }
+          value += String.fromCharCode(charCode);
+          position += 4;
+          break;
+        }
+        default:
+          throw syntaxError(
+            source,
+            position,
+            `Invalid character escape sequence: \\${String.fromCharCode(
+              code,
+            )}.`,
+          );
+      }
+      ++position;
+      chunkStart = position;
+    }
+  }
+
+  throw syntaxError(source, position, 'Unterminated string.');
+}
+
+/**
+ * Reads a block string token from the source file.
+ *
+ * """("?"?(\\"""|\\(?!=""")|[^"\\]))*"""
+ */
+function readBlockString(source, start, line, col, prev, lexer): Token {
+  const body = source.body;
+  let position = start + 3;
+  let chunkStart = position;
+  let code = 0;
+  let rawValue = '';
+
+  while (position < body.length && !isNaN((code = body.charCodeAt(position)))) {
+    // Closing Triple-Quote (""")
+    if (
+      code === 34 &&
+      body.charCodeAt(position + 1) === 34 &&
+      body.charCodeAt(position + 2) === 34
+    ) {
+      rawValue += body.slice(chunkStart, position);
+      return new Tok(
+        TokenKind.BLOCK_STRING,
+        start,
+        position + 3,
+        line,
+        col,
+        prev,
+        dedentBlockStringValue(rawValue),
+      );
+    }
+
+    // SourceCharacter
+    if (
+      code < 0x0020 &&
+      code !== 0x0009 &&
+      code !== 0x000a &&
+      code !== 0x000d
+    ) {
+      throw syntaxError(
+        source,
+        position,
+        `Invalid character within String: ${printCharCode(code)}.`,
+      );
+    }
+
+    if (code === 10) {
+      // new line
+      ++position;
+      ++lexer.line;
+      lexer.lineStart = position;
+    } else if (code === 13) {
+      // carriage return
+      if (body.charCodeAt(position + 1) === 10) {
+        position += 2;
+      } else {
+        ++position;
+      }
+      ++lexer.line;
+      lexer.lineStart = position;
+    } else if (
+      // Escape Triple-Quote (\""")
+      code === 92 &&
+      body.charCodeAt(position + 1) === 34 &&
+      body.charCodeAt(position + 2) === 34 &&
+      body.charCodeAt(position + 3) === 34
+    ) {
+      rawValue += body.slice(chunkStart, position) + '"""';
+      position += 4;
+      chunkStart = position;
+    } else {
+      ++position;
+    }
+  }
+
+  throw syntaxError(source, position, 'Unterminated string.');
+}
+
+/**
+ * Converts four hexadecimal chars to the integer that the
+ * string represents. For example, uniCharCode('0','0','0','f')
+ * will return 15, and uniCharCode('0','0','f','f') returns 255.
+ *
+ * Returns a negative number on error, if a char was invalid.
+ *
+ * This is implemented by noting that char2hex() returns -1 on error,
+ * which means the result of ORing the char2hex() will also be negative.
+ */
+function uniCharCode(a, b, c, d) {
+  return (
+    (char2hex(a) << 12) | (char2hex(b) << 8) | (char2hex(c) << 4) | char2hex(d)
+  );
+}
+
+/**
+ * Converts a hex character to its integer value.
+ * '0' becomes 0, '9' becomes 9
+ * 'A' becomes 10, 'F' becomes 15
+ * 'a' becomes 10, 'f' becomes 15
+ *
+ * Returns -1 on error.
+ */
+function char2hex(a) {
+  return a >= 48 && a <= 57
+    ? a - 48 // 0-9
+    : a >= 65 && a <= 70
+    ? a - 55 // A-F
+    : a >= 97 && a <= 102
+    ? a - 87 // a-f
+    : -1;
+}
+
+/**
+ * Reads an alphanumeric + underscore name from the source.
+ *
+ * [_A-Za-z][_0-9A-Za-z]*
+ */
+function readName(source, start, line, col, prev): Token {
+  const body = source.body;
+  const bodyLength = body.length;
+  let position = start + 1;
+  let code = 0;
+  while (
+    position !== bodyLength &&
+    !isNaN((code = body.charCodeAt(position))) &&
+    (code === 95 || // _
+    (code >= 48 && code <= 57) || // 0-9
+    (code >= 65 && code <= 90) || // A-Z
+      (code >= 97 && code <= 122)) // a-z
+  ) {
+    ++position;
+  }
+  return new Tok(
+    TokenKind.NAME,
+    start,
+    position,
+    line,
+    col,
+    prev,
+    body.slice(start, position),
+  );
+}