Class: CPreprocessorConditionals

Inherits:
Object
  • Object
show all
Defined in:
lib/ceedling/preprocess/c_preprocessor_conditionals.rb

Overview

Lightweight C Preprocessor Conditional Block Tracker

Tracks the active/inactive state of C conditional blocks (#ifdef/#ifndef/#if/#elif/#else/#endif) against a list of defined macro names. Intended for use in text-only (fallback) preprocessing paths where a real C preprocessor is unavailable.

Feed one logical line at a time to process_directive. After each call, active? returns whether the current position is inside an active block. Nesting is fully tracked via a stack.

Evaluation rules:

#ifdef  MACRO          → active when MACRO is in defines list
#ifndef MACRO          → active when MACRO is NOT in defines list
#if 0                  → always inactive
#if 1                  → always active
#if defined(MACRO)     → active when MACRO in defines list
#if !defined(MACRO)    → active when MACRO NOT in defines list
#elif defined(MACRO)   → active when prior branch was inactive AND MACRO in defines
#else                  → active when all prior branches were inactive
#endif                 → pops the innermost stack frame
Complex #if expression → treated as active (conservative: include the block)

Expects lines pre-cleaned by code_lines / clean_encoding (comments stripped, continuations joined). Does not raise on multi-byte characters.

Known limitation: A #ifdef appearing inside a multi-line C block comment may be misidentified as a real directive if the caller uses raw (non-comment- stripped) lines. This is an accepted limitation of lightweight text processing.

Instance Method Summary collapse

Constructor Details

#initialize(defines) ⇒ CPreprocessorConditionals

Returns a new instance of CPreprocessorConditionals.



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# File 'lib/ceedling/preprocess/c_preprocessor_conditionals.rb', line 44

def initialize(defines)
  # Normalize defines array: strip leading -D, strip =value suffix, keep name only
  @defined_macros = normalize_defines(defines)
  @stack = []  # Each frame: {active: bool, seen_true_branch: bool}
end

Instance Method Details

#active? ⇒ Boolean

True when the current position is inside an active conditional block (or outside all blocks, which is always active).

Returns:

  • (Boolean) 


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# File 'lib/ceedling/preprocess/c_preprocessor_conditionals.rb', line 104

def active?
  # If outside all blocks, active by default.
  # Otherwise, the innermost frame must be active.
  return true if @stack.empty?
  @stack.last[:active]
end

#process_directive(line) ⇒ Object

Feed one logical, comment-stripped, continuation-joined line. Updates the conditional block state.



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# File 'lib/ceedling/preprocess/c_preprocessor_conditionals.rb', line 52

def process_directive(line)
  _line = line.clean_encoding.lstrip

  case _line
  when /^#\s*ifdef\s+(\w+)/
    push( macro_defined?($1) )

  when /^#\s*ifndef\s+(\w+)/
    push( !macro_defined?($1) )

  when /^#\s*if\s+0\b/
    push( false )

  when /^#\s*if\s+1\b/
    push( true )

  when /^#\s*if\s+!\s*defined\s*\(\s*(\w+)\s*\)/
    push( !macro_defined?($1) )

  when /^#\s*if\s+defined\s*\(\s*(\w+)\s*\)/
    push( macro_defined?($1) )

  when /^#\s*if\b/
    # Complex or unrecognized #if expression — treat as active (conservative)
    push( true )

  when /^#\s*elif\s+!\s*defined\s*\(\s*(\w+)\s*\)/
    handle_elif( !macro_defined?($1) )

  when /^#\s*elif\s+defined\s*\(\s*(\w+)\s*\)/
    handle_elif( macro_defined?($1) )

  when /^#\s*elif\s+0\b/
    handle_elif( false )

  when /^#\s*elif\s+1\b/
    handle_elif( true )

  when /^#\s*elif\b/
    # Complex or unrecognized #elif expression — treat as active (conservative)
    handle_elif( true )

  when /^#\s*else\b/
    handle_else

  when /^#\s*endif\b/
    @stack.pop unless @stack.empty?
  end
end

#reset ⇒ Object

Reset state for reuse (e.g. across multiple files)



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# File 'lib/ceedling/preprocess/c_preprocessor_conditionals.rb', line 112

def reset
  @stack.clear
end