# Option `--dump`¶ ↑

For other argument values, see Option –dump.

For the examples here, we use this program:

    $ cat t.rb
    puts 'Foo'

The supported dump items:

- `insns`: Instruction sequences:

      $ ruby --dump=insns t.rb
      == disasm: #<ISeq:<main>@t.rb:1 (1,0)-(1,10)> (catch: FALSE)
      0000 putself                                                          (   1)[Li]
      0001 putstring                              "Foo"
      0003 opt_send_without_block                 <calldata!mid:puts, argc:1, FCALL|ARGS_SIMPLE>
      0005 leave

- `parsetree`: Abstract syntax tree (AST):

      $ ruby --dump=parsetree t.rb
      ###########################################################
      ## Do NOT use this node dump for any purpose other than  ##
      ## debug and research.  Compatibility is not guaranteed. ##
      ###########################################################

      # @ NODE_SCOPE (line: 1, location: (1,0)-(1,10))
      # +- nd_tbl: (empty)
      # +- nd_args:
      # |   (null node)
      # +- nd_body:
      #     @ NODE_FCALL (line: 1, location: (1,0)-(1,10))*
      #     +- nd_mid: :puts
      #     +- nd_args:
      #         @ NODE_LIST (line: 1, location: (1,5)-(1,10))
      #         +- nd_alen: 1
      #         +- nd_head:
      #         |   @ NODE_STR (line: 1, location: (1,5)-(1,10))
      #         |   +- nd_lit: "Foo"
      #         +- nd_next:
      #             (null node)

- `yydebug`: Debugging information from yacc parser generator:

      $ ruby --dump=yydebug t.rb
      Starting parse
      Entering state 0
      Reducing stack by rule 1 (line 1295):
      lex_state: NONE -> BEG at line 1296
      vtable_alloc:12392: 0x0000558453df1a00
      vtable_alloc:12393: 0x0000558453df1a60
      cmdarg_stack(push): 0 at line 12406
      cond_stack(push): 0 at line 12407
      -> $$ = nterm $@1 (1.0-1.0: )
      Stack now 0
      Entering state 2
      Reading a token:
      lex_state: BEG -> CMDARG at line 9049
      Next token is token "local variable or method" (1.0-1.4: puts)
      Shifting token "local variable or method" (1.0-1.4: puts)
      Entering state 35
      Reading a token: Next token is token "string literal" (1.5-1.6: )
      Reducing stack by rule 742 (line 5567):
      $1 = token "local variable or method" (1.0-1.4: puts)
      -> $$ = nterm operation (1.0-1.4: )
      Stack now 0 2
      Entering state 126
      Reducing stack by rule 78 (line 1794):
      $1 = nterm operation (1.0-1.4: )
      -> $$ = nterm fcall (1.0-1.4: )
      Stack now 0 2
      Entering state 80
      Next token is token "string literal" (1.5-1.6: )
      Reducing stack by rule 292 (line 2723):
      cmdarg_stack(push): 1 at line 2737
      -> $$ = nterm $@16 (1.4-1.4: )
      Stack now 0 2 80
      Entering state 235
      Next token is token "string literal" (1.5-1.6: )
      Shifting token "string literal" (1.5-1.6: )
      Entering state 216
      Reducing stack by rule 607 (line 4706):
      -> $$ = nterm string_contents (1.6-1.6: )
      Stack now 0 2 80 235 216
      Entering state 437
      Reading a token: Next token is token "literal content" (1.6-1.9: "Foo")
      Shifting token "literal content" (1.6-1.9: "Foo")
      Entering state 503
      Reducing stack by rule 613 (line 4802):
      $1 = token "literal content" (1.6-1.9: "Foo")
      -> $$ = nterm string_content (1.6-1.9: )
      Stack now 0 2 80 235 216 437
      Entering state 507
      Reducing stack by rule 608 (line 4716):
      $1 = nterm string_contents (1.6-1.6: )
      $2 = nterm string_content (1.6-1.9: )
      -> $$ = nterm string_contents (1.6-1.9: )
      Stack now 0 2 80 235 216
      Entering state 437
      Reading a token:
      lex_state: CMDARG -> END at line 7276
      Next token is token "terminator" (1.9-1.10: )
      Shifting token "terminator" (1.9-1.10: )
      Entering state 508
      Reducing stack by rule 590 (line 4569):
      $1 = token "string literal" (1.5-1.6: )
      $2 = nterm string_contents (1.6-1.9: )
      $3 = token "terminator" (1.9-1.10: )
      -> $$ = nterm string1 (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 109
      Reducing stack by rule 588 (line 4559):
      $1 = nterm string1 (1.5-1.10: )
      -> $$ = nterm string (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 108
      Reading a token:
      lex_state: END -> BEG at line 9200
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 586 (line 4541):
      $1 = nterm string (1.5-1.10: )
      -> $$ = nterm strings (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 107
      Reducing stack by rule 307 (line 2837):
      $1 = nterm strings (1.5-1.10: )
      -> $$ = nterm primary (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 90
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 261 (line 2553):
      $1 = nterm primary (1.5-1.10: )
      -> $$ = nterm arg (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 220
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 270 (line 2586):
      $1 = nterm arg (1.5-1.10: )
      -> $$ = nterm arg_value (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 221
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 297 (line 2779):
      $1 = nterm arg_value (1.5-1.10: )
      -> $$ = nterm args (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 224
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 772 (line 5626):
      -> $$ = nterm none (1.10-1.10: )
      Stack now 0 2 80 235 224
      Entering state 442
      Reducing stack by rule 296 (line 2773):
      $1 = nterm none (1.10-1.10: )

      -> $$ = nterm opt_block_arg (1.10-1.10: )
      Stack now 0 2 80 235 224
      Entering state 441
      Reducing stack by rule 288 (line 2696):
      $1 = nterm args (1.5-1.10: )
      $2 = nterm opt_block_arg (1.10-1.10: )
      -> $$ = nterm call_args (1.5-1.10: )
      Stack now 0 2 80 235
      Entering state 453
      Reducing stack by rule 293 (line 2723):
      $1 = nterm $@16 (1.4-1.4: )
      $2 = nterm call_args (1.5-1.10: )
      cmdarg_stack(pop): 0 at line 2754
      -> $$ = nterm command_args (1.4-1.10: )
      Stack now 0 2 80
      Entering state 333
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 79 (line 1804):
      $1 = nterm fcall (1.0-1.4: )
      $2 = nterm command_args (1.4-1.10: )
      -> $$ = nterm command (1.0-1.10: )
      Stack now 0 2
      Entering state 81
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 73 (line 1770):
      $1 = nterm command (1.0-1.10: )
      -> $$ = nterm command_call (1.0-1.10: )
      Stack now 0 2
      Entering state 78
      Reducing stack by rule 51 (line 1659):
      $1 = nterm command_call (1.0-1.10: )
      -> $$ = nterm expr (1.0-1.10: )
      Stack now 0 2
      Entering state 75
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 39 (line 1578):
      $1 = nterm expr (1.0-1.10: )
      -> $$ = nterm stmt (1.0-1.10: )
      Stack now 0 2
      Entering state 73
      Next token is token '\n' (1.10-1.10: )
      Reducing stack by rule 8 (line 1354):
      $1 = nterm stmt (1.0-1.10: )
      -> $$ = nterm top_stmt (1.0-1.10: )
      Stack now 0 2
      Entering state 72
      Reducing stack by rule 5 (line 1334):
      $1 = nterm top_stmt (1.0-1.10: )
      -> $$ = nterm top_stmts (1.0-1.10: )
      Stack now 0 2
      Entering state 71
      Next token is token '\n' (1.10-1.10: )
      Shifting token '\n' (1.10-1.10: )
      Entering state 311
      Reducing stack by rule 769 (line 5618):
      $1 = token '\n' (1.10-1.10: )
      -> $$ = nterm term (1.10-1.10: )
      Stack now 0 2 71
      Entering state 313
      Reducing stack by rule 770 (line 5621):
      $1 = nterm term (1.10-1.10: )
      -> $$ = nterm terms (1.10-1.10: )
      Stack now 0 2 71
      Entering state 314
      Reading a token: Now at end of input.
      Reducing stack by rule 759 (line 5596):
      $1 = nterm terms (1.10-1.10: )
      -> $$ = nterm opt_terms (1.10-1.10: )
      Stack now 0 2 71
      Entering state 312
      Reducing stack by rule 3 (line 1321):
      $1 = nterm top_stmts (1.0-1.10: )
      $2 = nterm opt_terms (1.10-1.10: )
      -> $$ = nterm top_compstmt (1.0-1.10: )
      Stack now 0 2
      Entering state 70
      Reducing stack by rule 2 (line 1295):
      $1 = nterm $@1 (1.0-1.0: )
      $2 = nterm top_compstmt (1.0-1.10: )
      vtable_free:12426: p->lvtbl->args(0x0000558453df1a00)
      vtable_free:12427: p->lvtbl->vars(0x0000558453df1a60)
      cmdarg_stack(pop): 0 at line 12428
      cond_stack(pop): 0 at line 12429
      -> $$ = nterm program (1.0-1.10: )
      Stack now 0
      Entering state 1
      Now at end of input.
      Shifting token "end-of-input" (1.10-1.10: )
      Entering state 3
      Stack now 0 1 3
      Cleanup: popping token "end-of-input" (1.10-1.10: )
      Cleanup: popping nterm program (1.0-1.10: )

Additional flags can follow dump items.

- `+comment`: Add comments to AST.

- `+error-tolerant`: Parse in error-tolerant mode.

- `-optimize`: Disable optimizations for instruction sequences.