Module: MilkTea::Parser::Statements

Included in:
MilkTea::Parser
Defined in:
lib/milk_tea/core/parser/statements.rb

Instance Method Summary collapse

Instance Method Details

#check_inline_stmt_start? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 6

def check_inline_stmt_start?
  return false unless check(:inline)

  next_idx = @current + 1
  return false if next_idx >= @tokens.length

  next_token = @tokens[next_idx]
  %i[for while match if].include?(next_token.type)
end

#check_parallel_block_start? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 25

def check_parallel_block_start?
  return false unless check(:parallel)

  next_idx = @current + 1
  return false if next_idx >= @tokens.length

  @tokens[next_idx].type == :colon
end

#check_parallel_for_start? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 16

def check_parallel_for_start?
  return false unless check(:parallel)

  next_idx = @current + 1
  return false if next_idx >= @tokens.length

  @tokens[next_idx].type == :for
end

#check_when_start? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 34

def check_when_start?
  check(:when)
end

#inline_block_body? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 278

def inline_block_body?
  check(:colon) && @current + 1 < @tokens.length && @tokens[@current + 1].type != :newline
end

#match_arm_expression_form? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/milk_tea/core/parser/statements.rb', line 441

def match_arm_expression_form?
  check(:colon) && @current + 1 < @tokens.length && @tokens[@current + 1].type != :newline
end

#normalize_mixed_match_arms(arms) ⇒ Object

A statement match may mix inline value arms (pattern: expr) with block arms. The inline form is a single expression statement, so when any arm is a block the inline arms are rewritten to block arms with a single expression-statement body. This keeps MatchStmt arms homogeneous (all MatchArm) and MatchExpr arms homogeneous (all MatchExprArm); the sema / control-flow / lowering consumers rely on that invariant.



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# File 'lib/milk_tea/core/parser/statements.rb', line 346

def normalize_mixed_match_arms(arms)
  return arms unless arms.any? { |arm| arm.is_a?(AST::MatchExprArm) } && arms.any? { |arm| arm.is_a?(AST::MatchArm) }

  arms.map do |arm|
    if arm.is_a?(AST::MatchExprArm)
      AST::MatchArm.new(
        pattern: arm.pattern,
        binding_name: arm.binding_name,
        binding_line: arm.binding_line,
        binding_column: arm.binding_column,
        body: [AST::ExpressionStmt.new(expression: arm.value, line: arm.line)],
        line: arm.line,
        column: arm.column,
      )
    else
      arm
    end
  end
end

#parse_assignment_or_expression_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 792

def parse_assignment_or_expression_stmt
  line = peek.line
  expression = parse_expression
  if match(*Token::ASSIGNMENT_TYPES)
    operator = previous.lexeme
    column = previous.column
    value = parse_expression
    finish_expression_statement(value)
    AST::Assignment.new(target: expression, operator:, value:, line:, column:)
  else
    finish_expression_statement(expression)
    AST::ExpressionStmt.new(expression:, line:)
  end
end

#parse_break_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 598

def parse_break_stmt
  token = previous
  line = token.line
  consume_end_of_statement
  AST::BreakStmt.new(line:, column: token.column, length: token.lexeme.length)
end

#parse_continue_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 605

def parse_continue_stmt
  token = previous
  line = token.line
  consume_end_of_statement
  AST::ContinueStmt.new(line:, column: token.column, length: token.lexeme.length)
end

#parse_decl_when_arms ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 648

def parse_decl_when_arms
  consume(:colon, "expected ':' before block")
  consume(:newline, "expected newline before block")
  consume(:indent, "expected indented block")

  arms = []
  skip_newlines
  until check(:dedent) || eof?
    pattern = parse_expression
    binding_name = if match(:as)
                      binding_token = consume_name("expected binding name after 'as'")
                      binding_token.lexeme
                    end
    body = parse_declaration_block
    binding_token ||= previous
    arms << AST::WhenBranch.new(
      pattern:,
      binding_name:,
      binding_line: binding_token.line,
      binding_column: binding_token.column,
      body:,
      line: pattern.line,
      column: pattern.column,
    )
    skip_newlines
  end

  consume(:dedent, "expected end of block")
  arms
end

#parse_defer_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 620

def parse_defer_stmt
  token = previous
  line = token.line
  body = parse_inline_or_block_body("after defer")
  AST::DeferStmt.new(body:, line:, column: token.column, length: token.lexeme.length)
end

#parse_destructure_pattern ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 191

def parse_destructure_pattern
  match(:lparen)
  bindings = []
  loop do
    token = consume_name("expected binding name in destructure pattern")
    bindings << token.lexeme
    break unless match(:comma)
  end
  consume(:rparen, "expected ')' after destructure pattern")
  bindings
end

#parse_else_branch_body ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 258

def parse_else_branch_body
  if inline_block_body?
    consume(:colon, "expected ':' before else body")
    @in_inline_block_body = true
    result = [parse_statement]
    @in_inline_block_body = false
    result
  else
    parse_block
  end
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  raise unless recovered_body

  recovered_body
end

#parse_emit_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 474

def parse_emit_stmt
  line = previous.line
  column = previous.column
  decl = parse_declaration
  AST::EmitStmt.new(declaration: decl, line:, column:)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  synchronize_to_statement_boundary
  AST::EmitStmt.new(declaration: AST::ErrorExpr.new(message: e.message), line:, column:)
end

#parse_for_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 487

def parse_for_stmt
  line = previous.line
  bindings = []
  iterables = nil
  loop do
    name_token = consume_name("expected loop variable name")
    bindings << AST::ForBinding.new(name: name_token.lexeme, line: name_token.line, column: name_token.column)
    break unless match(:comma)
  end
  consume(:in, "expected 'in' in for loop")
  iterables = [parse_expression]
  iterables << parse_expression while match(:comma)
  body = parse_inline_or_block_body("after 'in' iterables")
  AST::ForStmt.new(bindings:, iterables:, body:, line:, column: bindings.first.column)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(
    e,
    recovered_body,
    header_type: :for,
    header_bindings: bindings.empty? ? nil : bindings,
    header_iterables: iterables&.any? ? iterables : nil,
  ) if recovered_body

  recovery_error_stmt(e)
end

#parse_gather_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 556

def parse_gather_stmt
  line = previous.line
  column = previous.column
  handles = []
  handle = parse_expression
  handles << handle
  while match(:comma)
    handle = parse_expression
    handles << handle
  end
  AST::GatherStmt.new(handles:, line:, column:)
end

#parse_if_branch(token) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 223

def parse_if_branch(token)
  condition = nil
  condition = parse_expression
  body = if inline_block_body?
           consume(:colon, "expected ':' after if condition")
           @in_inline_block_body = true
           result = [parse_statement]
           @in_inline_block_body = false
           result
         else
           parse_block
         end
  AST::IfBranch.new(
    condition:,
    body:,
    line: token.line,
    column: token.column,
    length: token.lexeme.length,
  )
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  raise unless recovered_body

  AST::IfBranch.new(
    condition: condition || recovery_error_expr(e),
    body: recovered_body,
    line: token.line,
    column: token.column,
    length: token.lexeme.length,
  )
end

#parse_if_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 203

def parse_if_stmt
  line = previous.line
  branches = [parse_if_branch(previous)]

  while check(:else) && check_next(:if)
    advance
    advance
    branches << parse_if_branch(previous)
  end

  else_line = nil
  else_column = nil
  else_body = if match(:else)
                else_line = previous.line
                else_column = previous.column
                parse_else_branch_body
              end
  AST::IfStmt.new(branches:, else_body:, line:, else_line:, else_column:)
end

#parse_inline_for_stmt(_inline_token) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 715

def parse_inline_for_stmt(_inline_token)
  line = previous.line
  bindings = []
  iterables = nil
  loop do
    name_token = consume_name("expected loop variable name")
    bindings << AST::ForBinding.new(name: name_token.lexeme, line: name_token.line, column: name_token.column)
    break unless match(:comma)
  end
  consume(:in, "expected 'in' in for loop")
  iterables = [parse_expression]
  iterables << parse_expression while match(:comma)
  body = parse_inline_or_block_body("after 'in' iterables")
  AST::ForStmt.new(bindings:, iterables:, body:, inline: true, line:, column: bindings.first.column)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(e, recovered_body, header_type: :for) if recovered_body

  recovery_error_stmt(e)
end

#parse_inline_if_stmt(inline_token) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 777

def parse_inline_if_stmt(inline_token)
  token = previous
  line = token.line
  branches = [parse_if_branch(token)]

  while check(:else) && check_next(:if)
    advance
    advance
    branches << parse_if_branch(previous)
  end

  else_body = match(:else) ? parse_else_branch_body : nil
  AST::IfStmt.new(branches:, else_body:, inline: true, line:)
end

#parse_inline_match_stmt(inline_token) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 760

def parse_inline_match_stmt(inline_token)
  token = previous
  line = token.line
  arms = []
  expression = parse_expression
  arms = normalize_mixed_match_arms(parse_match_arms(arms))
  AST::MatchStmt.new(expression:, arms:, inline: true, line:, column: token.column, length: token.lexeme.length)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_arms = synchronize_to_match_arm_boundary
  return AST::MatchStmt.new(expression: expression || recovery_error_expr(e), arms: normalize_mixed_match_arms(arms + recovered_arms), inline: true, line:, column: token.column, length: token.lexeme.length) if recovered_arms

  recovery_error_stmt(e)
end

#parse_inline_or_block_body(message) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 282

def parse_inline_or_block_body(message)
  if inline_block_body?
    consume(:colon, "expected ':' #{message}")
    @in_inline_block_body = true
    result = [parse_statement]
    @in_inline_block_body = false
    result
  else
    parse_block
  end
end

#parse_inline_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 700

def parse_inline_stmt
  token = previous
  if match(:for)
    parse_inline_for_stmt(token)
  elsif match(:while)
    parse_inline_while_stmt(token)
  elsif match(:match)
    parse_inline_match_stmt(token)
  elsif match(:if)
    parse_inline_if_stmt(token)
  else
    raise error(peek, "expected for, while, match, or if after inline")
  end
end

#parse_inline_while_stmt(inline_token) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 739

def parse_inline_while_stmt(inline_token)
  line = inline_token.line
  condition = parse_expression
  body = parse_inline_or_block_body("after inline while condition")
  AST::WhileStmt.new(condition:, body:, inline: true, line:, column: inline_token.column, length: inline_token.lexeme.length)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return AST::WhileStmt.new(
    condition: condition || recovery_error_expr(e),
    body: recovered_body,
    line:,
    column: inline_token.column,
    length: inline_token.lexeme.length,
  ) if recovered_body

  recovery_error_stmt(e)
end

#parse_local_decl(kind) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 97

def parse_local_decl(kind)
  line = previous.line
  column = previous.column
  name_token = nil
  name = nil
  var_type = nil

  destructure_bindings = nil
  destructure_type_name = nil
  if check(:lparen)
    destructure_bindings = parse_destructure_pattern
  elsif check_name && check_next(:lparen)
    destructure_type_name = advance.lexeme
    destructure_bindings = parse_destructure_pattern
  elsif check_name && check_next(:dot)
    parts = [advance.lexeme]
    while check(:dot)
      advance
      parts << consume_name("expected type name after '.' in destructure pattern").lexeme
    end
    if match(:lparen)
      destructure_type_name = parts.length == 1 ? parts[0].dup : parts
      destructure_bindings = parse_destructure_pattern
    else
      raise error(@tokens[@current], "expected '(' after type name in destructure pattern")
    end
  else
    name_token = consume_name("expected local variable name")
    name = name_token.lexeme
  end

  var_type = match(:colon) ? parse_type_ref : nil
  value = nil
  else_binding = nil
  else_body = nil
  else_started = false

  if destructure_bindings
    consume(:equal, "expected '=' after destructure pattern")
    value = parse_expression
    consume_end_of_statement
  elsif match(:equal)
    value = parse_expression
    if match(:else)
      else_started = true

      if match(:as)
        binding_token = consume_name("expected error binding name after 'as'")
        else_binding = AST::Identifier.new(name: binding_token.lexeme, line: binding_token.line, column: binding_token.column)
      end

      else_body = parse_block
    else
      finish_expression_statement(value)
    end
  else
    raise error(name_token, "local declaration without initializer requires a type") unless var_type

    consume_end_of_statement
  end

  AST::LocalDecl.new(kind:, name:, type: var_type, value:, else_binding:, else_body:, line:, column: name_token&.column || column, destructure_bindings:, destructure_type_name:)
rescue ParseError => e
  raise unless @recovery_errors && name

  @recovery_errors << e
  synchronize_to_statement_boundary

  if else_started
    return AST::LocalDecl.new(
      kind:,
      name:,
      type: var_type,
      value:,
      else_binding:,
      else_body: nil,
      line:,
      column: name_token.column,
      recovered_else: true,
    )
  end

  AST::LocalDecl.new(
    kind:,
    name:,
    type: var_type,
    value: recovery_error_expr(e),
    else_binding: nil,
    else_body: nil,
    line:,
    column: name_token.column,
  )
end

#parse_match_arm ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 376

def parse_match_arm
  patterns = []
  binding_token = nil
  binding_name = nil

  if match(:else)
    patterns << AST::Identifier.new(name: "_", line: previous.line, column: previous.column)
  else
    patterns << parse_match_arm_pattern
    while match(:pipe)
      patterns << parse_match_arm_pattern
    end
  end
  binding_name = if match(:as)
                   binding_token = consume_name("expected binding name after 'as'")
                   binding_token.lexeme
                 end

  if match_arm_expression_form?
    consume(:colon, "expected ':' after match expression arm pattern")
    value = parse_expression
    finish_expression_statement(value)
    patterns.map do |pattern|
      AST::MatchExprArm.new(
        pattern:,
        binding_name:,
        binding_line: binding_token&.line,
        binding_column: binding_token&.column,
        value:,
        line: pattern.line,
        column: pattern.column,
      )
    end
  else
    body = parse_block
    patterns.map do |pattern|
      AST::MatchArm.new(
        pattern:,
        binding_name:,
        binding_line: binding_token&.line,
        binding_column: binding_token&.column,
        body:,
        line: pattern.line,
        column: pattern.column,
      )
    end
  end
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return [AST::MatchArm.new(
    pattern: patterns.first || recovery_error_expr(e),
    binding_name:,
    binding_line: binding_token&.line,
    binding_column: binding_token&.column,
    body: recovered_body,
    line: patterns.first&.line,
    column: patterns.first&.column,
  )] if recovered_body

  raise
end

#parse_match_arm_body(arms = []) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 366

def parse_match_arm_body(arms = [])
  skip_newlines
  until check(:dedent) || eof?
    arms.concat(parse_match_arm)
    skip_newlines
  end

  arms
end

#parse_match_arms(arms = []) ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 328

def parse_match_arms(arms = [])
  consume(:colon, "expected ':' before block")
  consume(:newline, "expected newline before block")
  consume(:indent, "expected indented block")

  parse_match_arm_body(arms)

  consume(:dedent, "expected end of block")
  arms
end

#parse_match_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 294

def parse_match_stmt
  token = previous
  line = token.line
  expression = nil
  arms = []
  expression = parse_expression
  arms = normalize_mixed_match_arms(parse_match_arms(arms))
  if arms.first&.is_a?(AST::MatchExprArm)
    expr = AST::MatchExpr.new(expression:, arms:, line:, column: token.column, length: token.lexeme.length)
    AST::ExpressionStmt.new(expression: expr, line:)
  else
    AST::MatchStmt.new(expression:, arms:, line:, column: token.column, length: token.lexeme.length)
  end
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_arms = synchronize_to_match_arm_boundary
  target_line = line
  if recovered_arms
    combined_arms = normalize_mixed_match_arms(arms + recovered_arms)
    stmt =
      if combined_arms.first&.is_a?(AST::MatchExprArm)
        expr = AST::MatchExpr.new(expression: expression || recovery_error_expr(e), arms: combined_arms, line: target_line, column: token.column, length: token.lexeme.length)
        AST::ExpressionStmt.new(expression: expr, line: target_line)
      else
        AST::MatchStmt.new(expression: expression || recovery_error_expr(e), arms: combined_arms, line: target_line, column: token.column, length: token.lexeme.length)
      end
    return stmt
  end

  recovery_error_stmt(e)
end

#parse_parallel_block_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 536

def parse_parallel_block_stmt
  line = previous.line
  column = previous.column
  consume(:colon, "expected ':' after 'parallel'")
  consume(:newline, "expected newline after 'parallel:'")
  consume(:indent, "expected indented block after 'parallel:'")
  statements = parse_statement_block_body
  consume(:dedent, "expected end of parallel block")
  bodies = statements.map { |stmt| [stmt] }
  AST::ParallelBlockStmt.new(bodies:, line:, column:)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(e, recovered_body, header_type: :parallel) if recovered_body

  recovery_error_stmt(e)
end

#parse_parallel_for_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 517

def parse_parallel_for_stmt
  consume(:for, "expected 'for' after 'parallel'")
  line = previous.line
  name_token = consume_name("expected loop variable name")
  bindings = [AST::ForBinding.new(name: name_token.lexeme, line: name_token.line, column: name_token.column)]
  consume(:in, "expected 'in' in parallel for loop")
  iterables = [parse_expression]
  body = parse_block
  AST::ForStmt.new(bindings:, iterables:, body:, threaded: true, line:, column: bindings.first.column)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(e, recovered_body, header_type: :for) if recovered_body

  recovery_error_stmt(e)
end

#parse_pass_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 591

def parse_pass_stmt
  token = previous
  line = token.line
  consume_end_of_statement
  AST::PassStmt.new(line:, column: token.column, length: token.lexeme.length)
end

#parse_return_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 612

def parse_return_stmt
  token = previous
  line = token.line
  value = check(:newline) ? nil : parse_expression
  finish_expression_statement(value)
  AST::ReturnStmt.new(value:, line:, column: token.column, length: token.lexeme.length)
end

#parse_statement ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 48

def parse_statement
  reject_operator_statement_start!
  if match(:let)
    parse_local_decl(:let)
  elsif match(:var)
    parse_local_decl(:var)
  elsif match(:if)
    parse_if_stmt
  elsif match(:match)
    parse_match_stmt
  elsif match(:unsafe)
    parse_unsafe_stmt
  elsif match(:static_assert)
    parse_static_assert
  elsif match(:emit)
    parse_emit_stmt
  elsif match(:for)
    parse_for_stmt
  elsif check_parallel_for_start?
    advance
    parse_parallel_for_stmt
  elsif check_parallel_block_start?
    advance
    parse_parallel_block_stmt
  elsif match(:gather)
    parse_gather_stmt
  elsif match(:while)
    parse_while_stmt
  elsif match(:pass)
    parse_pass_stmt
  elsif match(:break)
    parse_break_stmt
  elsif match(:continue)
    parse_continue_stmt
  elsif match(:return)
    parse_return_stmt
  elsif match(:defer)
    parse_defer_stmt
  elsif check_inline_stmt_start?
    advance
    parse_inline_stmt
  elsif check_when_start?
    advance
    parse_when_stmt
  else
    parse_assignment_or_expression_stmt
  end
end

#parse_static_assert ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 463

def parse_static_assert
  line = previous.line
  consume(:lparen, "expected '(' after static_assert")
  condition = parse_expression
  consume(:comma, "expected ',' after static_assert condition")
  message = parse_expression
  consume(:rparen, "expected ')' after static_assert message")
  consume_end_of_statement
  AST::StaticAssert.new(condition:, message:, line:)
end

#parse_unsafe_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 445

def parse_unsafe_stmt
  token = previous
  consume(:colon, "expected ':' after unsafe")
  body = if match(:newline)
           consume(:indent, "expected indented block")

           statements = parse_statement_block_body
           consume(:dedent, "expected end of block")
           statements
         else
           statement = parse_statement
           raise ParseError.new("inline unsafe local declarations must use expression form", token:, path: @path) if statement.is_a?(AST::LocalDecl)

           [statement]
         end
  AST::UnsafeStmt.new(body:, line: token.line, column: token.column, length: token.lexeme.length)
end

#parse_when_decl ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 627

def parse_when_decl
  token = previous
  line = token.line
  discriminant = parse_expression
  branches = parse_decl_when_arms
  else_body = if check(:else)
    if check_next(:newline) || check_next(:indent)
      parse_declaration_block
    end
  end
  AST::WhenStmt.new(discriminant:, branches:, else_body:, line:, column: token.column, length: token.lexeme.length)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(e, recovered_body, header_type: :when) if recovered_body

  recovery_error_stmt(e)
end

#parse_when_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 679

def parse_when_stmt
  token = previous
  line = token.line
  discriminant = parse_expression
  branches = normalize_mixed_match_arms(parse_match_arms([]))
  else_body = if check(:else)
    if check_next(:newline) || check_next(:indent)
      parse_else_branch_body
    end
  end
  AST::WhenStmt.new(discriminant:, branches:, else_body:, line:, column: token.column, length: token.lexeme.length)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return recovery_error_block_stmt(e, recovered_body, header_type: :when) if recovered_body

  recovery_error_stmt(e)
end

#parse_while_stmt ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 569

def parse_while_stmt
  token = previous
  line = token.line
  condition = parse_expression
  body = parse_inline_or_block_body("after while condition")
  AST::WhileStmt.new(condition:, body:, line:, column: token.column, length: token.lexeme.length)
rescue ParseError => e
  raise unless @recovery_errors

  @recovery_errors << e
  recovered_body = synchronize_to_statement_boundary
  return AST::WhileStmt.new(
    condition: condition || recovery_error_expr(e),
    body: recovered_body,
    line:,
    column: token.column,
    length: token.lexeme.length,
  ) if recovered_body

  recovery_error_stmt(e)
end

#reject_operator_statement_start! ⇒ Object 



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# File 'lib/milk_tea/core/parser/statements.rb', line 38

def reject_operator_statement_start!
  return unless Token::LINE_START_OPERATOR_TYPES.include?(peek.type)

  operator = peek.lexeme
  raise error(
    peek,
    "operator '#{operator}' cannot start a statement; end the previous line with it or wrap the expression in ( )"
  )
end