cppfront/source/to_cpp1.h at main · MaxSagebaum/cppfront · GitHub

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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

// Part of the Cppfront Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://github.com/hsutter/cppfront/blob/main/LICENSE for license information.

//===========================================================================

// Lowering to Cpp1 syntax

//===========================================================================

#ifndef CPP2_TO_CPP1_H

#define CPP2_TO_CPP1_H

#include "sema.h"

#include <filesystem>

namespace cpp2 {

//-----------------------------------------------------------------------

// Stringingizing helpers

//-----------------------------------------------------------------------

auto pad(int padding)

-> std::string_view

{

if (padding < 1) {

return "";

}

return {

indent_str.c_str(),

_as<size_t>( std::min( padding, _as<int>(std::ssize(indent_str))) )

};

}

auto multi_return_type_name(declaration_node const& n)

-> std::string

{

// When generating a multi-return struct, also enable multi-return

// from a (), [], or * operator. We can expand this in the future,

// but with care because most operators should 'do as the ints do'

// (e.g., it doesn't seem sensible for == to return multiple values)

constexpr std::pair<std::string_view, std::string_view> canonized_names[] = {

{ "operator()", "operator_call" },

{ "operator[]", "operator_subscript" },

{ "operator*", "operator_dereference" }

};

assert (n.is_function() && n.name());

auto ret = n.name()->to_string();

for (auto [op, canon] : canonized_names) {

if (ret == op) {

ret = canon;

break;

}

ret += "_ret";

return ret;

}

//-----------------------------------------------------------------------

// positional_printer: a Syntax 1 pretty printer

//-----------------------------------------------------------------------

static auto flag_emit_cppfront_info = false;

static cmdline_processor::register_flag cmd_emit_cppfront_info(

"emit-cppfront-info",

"Emit cppfront version/build in Cpp1 file",

[]{ flag_emit_cppfront_info = true; }

);

static auto flag_clean_cpp1 = false;

static cmdline_processor::register_flag cmd_clean_cpp1(

"clean-cpp1",

"Emit clean Cpp1 without #line directives",

[]{ flag_clean_cpp1 = true; }

);

static auto flag_line_paths = false;

static cmdline_processor::register_flag cmd_line_paths(

"line-paths",

"Emit absolute paths in #line directives",

[] { flag_line_paths = true; }

);

static auto flag_import_std = false;

static cmdline_processor::register_flag cmd_import_std(

"import-std",

"import all std:: via 'import std;' - ignored if -include-std is set",

[]{ flag_import_std = true; }

);

static auto flag_include_std = false;

static cmdline_processor::register_flag cmd_include_std(

"include-std",

"#include all std:: headers",

[]{ flag_include_std = true; }

);

static auto flag_cpp2_only = false;

static cmdline_processor::register_flag cmd_cpp2_only(

"pure-cpp2",

"Allow Cpp2 syntax only - also sets -import-std",

[]{ flag_cpp2_only = true; flag_import_std = true; }

);

static auto flag_safe_null_pointers = true;

static cmdline_processor::register_flag cmd_safe_null_pointers(

"no-null-checks",

"Disable null safety checks",

[]{ flag_safe_null_pointers = false; }

);

static auto flag_safe_zero_division = true;

static cmdline_processor::register_flag cmd_safe_zero_division(

"no-div-zero-checks",

"Disable integer division by zero checks",

[]{ flag_safe_zero_division = false; }

);

static auto flag_safe_subscripts = true;

static cmdline_processor::register_flag cmd_safe_subscripts(

"no-subscript-checks",

"Disable subscript safety checks",

[]{ flag_safe_subscripts = false; }

);

static auto flag_safe_comparisons = true;

static cmdline_processor::register_flag cmd_safe_comparisons(

"no-comparison-checks",

"Disable mixed-sign comparison safety checks",

[]{ flag_safe_comparisons = false; }

);

static auto flag_cpp1_filename = std::string{};

static cmdline_processor::register_flag cmd_cpp1_filename(

"output filename",

"Output to 'filename' (can be 'stdout') - default is *.cpp/*.h",

nullptr,

[](std::string const& name) { flag_cpp1_filename = name; }

);

static auto flag_cwd = std::filesystem::path{};

static cpp2::cmdline_processor::register_flag cmd_cwd(

"cwd path",

"Change current working directory to path",

nullptr,

[](std::string const& path) { flag_cwd = { path }; }

);

static auto flag_no_exceptions = false;

static cmdline_processor::register_flag cmd_no_exceptions(

"fno-exceptions",

"Disable C++ EH - failed 'as' for 'variant' will assert",

[]{ flag_no_exceptions = true; }

);

static auto flag_no_rtti = false;

static cmdline_processor::register_flag cmd_no_rtti(

"fno-rtti",

"Disable C++ RTTI - using 'as' for '*'/'std::any' will assert",

[]{ flag_no_rtti = true; }

);

struct text_with_pos{

std::string text;

source_position pos;

text_with_pos(std::string const& t, source_position p) : text{t}, pos{p} { }

};

class positional_printer

{

public:

positional_printer() = default;

private:

positional_printer(positional_printer const&) = delete;

void operator=(positional_printer const&) = delete;

// Core information

std::ofstream out_file = {}; // Cpp1 syntax output file

std::ostream* out = {}; // will point to out_file or cout

std::string cpp2_filename = {};

std::string cpp1_filename = {};

std::vector<comment> const* pcomments = {}; // Cpp2 comments data

source const* psource = {};

parser const* pparser = {};

source_position curr_pos = {}; // current (line,col) in output

lineno_t generated_pos_line = {}; // current line in generated output

int last_line_indentation = {};

int next_comment = 0; // index of the next comment not yet printed

bool last_was_empty = false;

int empty_lines_suppressed = 0;

bool just_printed_line_directive = false;

bool printed_extra = false;

char last_printed_char = {};

struct req_act_info {

colno_t requested;

colno_t offset;

req_act_info(colno_t r, colno_t o) : requested{r}, offset{o} { }

};

struct {

lineno_t line = {};

std::vector<req_act_info> requests = {};

} prev_line_info = {};

// Position override information

std::vector<source_position> preempt_pos = {}; // use this position instead of the next supplied one

int pad_for_this_line = 0; // extra padding to add/subtract for this line only

bool ignore_align = false;

int ignore_align_indent = 0;

lineno_t ignore_align_lineno = 0;

bool enable_indent_heuristic = true;

public:

// Modal information

enum phases : u8 {

phase0_type_decls = 0,

phase1_type_defs_func_decls = 1,

phase2_func_defs = 2

};

auto get_phase() const { return phase; }

private:

phases phase = phase0_type_decls;

auto inc_phase() -> void {

switch (phase) {

break;case phase0_type_decls : phase = phase1_type_defs_func_decls;

break;case phase1_type_defs_func_decls: phase = phase2_func_defs;

break;default : assert(false && "ICE: invalid lowering phase");

}

curr_pos = {};

next_comment = 0; // start over with the comments

}

std::vector<std::string*> emit_string_targets; // option to emit to string instead of out file

std::vector<std::vector<text_with_pos>*> emit_text_chunks_targets; // similar for vector<text_pos>

enum class target_type : u8 { string, chunks };

std::vector<target_type> emit_target_stack; // to interleave them sensibly

//-----------------------------------------------------------------------

// Print text

auto print(

std::string_view s,

source_position pos = source_position{},

bool track_curr_pos = true,

bool is_known_empty = false

)

-> void

{

// Take ownership of (and reset) just_printed_line_directive value

auto line_directive_already_done = std::exchange(just_printed_line_directive, false);

// If the caller is capturing this output, emit to the

// current target instead and skip most positioning logic

if (!emit_target_stack.empty())

{

// If capturing to a string, emit to the specified string

if (emit_target_stack.back() == target_type::string) {

assert(!emit_string_targets.empty());

*emit_string_targets.back() += s;

}

// If capturing to a vector of chunks, emit to that

else {

assert(!emit_text_chunks_targets.empty());

emit_text_chunks_targets.back()->insert( emit_text_chunks_targets.back()->begin(), text_with_pos(std::string(s), pos) );

}

return;

}

// Otherwise, we'll actually print the string to the output file

// and update our curr_pos position

if (s.length() > 0) {

last_printed_char = s.back();

}

// Reject consecutive empty lines: If this line is empty

if (

( s == "\n" || is_known_empty )

&& curr_pos.colno <= 1

)

{

// And so was the last one, update logical position only

// and increment empty_lines_suppressed instead of printing

if (last_was_empty) {

if (track_curr_pos) {

++curr_pos.lineno;

curr_pos.colno = 1;

}

++empty_lines_suppressed;

return;

}

// If this is the first consecutive empty, remember and continue

last_was_empty = true;

}

// Otherwise, if this line is not empty

else {

// Remember that this line was not empty

last_was_empty = false;

// And if we did suppress any empties, emit a #line to resync

if (empty_lines_suppressed > 0) {

if (!line_directive_already_done) {

print_line_directive(curr_pos.lineno);

}

empty_lines_suppressed = 0;

}

// Output the string

assert (out);

*out << s;

// Update curr_pos by finding how many line breaks s contained,

// and where the last one was which determines our current colno

if (track_curr_pos)

{

auto last_newline = s.npos; // the last newline we found in the string

auto newline_pos = std::size_t(0); // the current newline we found in the string

while ((newline_pos = s.find('\n', newline_pos)) != s.npos)

{

// For each line break we find, reset pad and inc current lineno

pad_for_this_line = 0;

++curr_pos.lineno;

last_newline = newline_pos;

++newline_pos;

}

// Now also adjust the colno

if (last_newline != s.npos) {

// If we found a newline, it's the distance from the last newline to EOL

curr_pos.colno = unchecked_narrow<colno_t>(s.length() - last_newline);

}

else {

// Else add the length of the string

curr_pos.colno += unchecked_narrow<colno_t>(s.length());

}

//-----------------------------------------------------------------------

// Internal helpers

// Start a new line if we're not in col 1 already

auto ensure_at_start_of_new_line()

-> void

{

if (curr_pos.colno > 1) {

auto old_pos = curr_pos;

print( "\n" );

assert(curr_pos.lineno == old_pos.lineno+1);

assert(curr_pos.colno == 1);

}

// Print a #line directive

auto print_line_directive( lineno_t line )

-> void

{

// Ignore requests from generated code (negative line numbers)

if (line < 1) {

return;

}

// Otherwise, implement the request

prev_line_info = { curr_pos.lineno, { } };

ensure_at_start_of_new_line();

// Not using print() here because this is transparent to the curr_pos

if (!flag_clean_cpp1) {

assert (out);

*out << "#line " << line << " " << std::quoted(cpp2_filename) << "\n";

}

just_printed_line_directive = true;

}

// Catch up with comment/blank lines

auto print_comment(comment const& c)

-> void

{

// For a line comment, start it at the right indentation and print it

// with a newline end

if (c.kind == comment::comment_kind::line_comment) {

print( pad( c.start.colno - curr_pos.colno + 1 ) );

print( c.text );

assert( c.text.find('\n') == c.text.npos ); // we shouldn't have newlines

print("\n");

}

// For a stream comment, pad out to its column (if we haven't passed it already)

// and emit it there

else {

print( pad( c.start.colno - curr_pos.colno ) );

print( c.text );

}

c.dbg_was_printed = true;

}

auto flush_comments( source_position pos )

-> void

{

if (!pcomments) {

return;

}

// For convenience

auto& comments = *pcomments;

// Add unprinted comments and blank lines as needed to catch up vertically

while (curr_pos.lineno < pos.lineno)

{

// If a comment goes on this line, print it

if (

next_comment < std::ssize(comments)

&& comments[next_comment].start.lineno <= curr_pos.lineno

)

{

// Emit non-function body comments in phase1_type_defs_func_decls,

// and emit function body comments in phase2_func_defs

assert(pparser);

if (

(

phase == phase1_type_defs_func_decls

&& !pparser->is_within_function_body( comments[next_comment].start.lineno )

)

(

phase == phase2_func_defs

&& pparser->is_within_function_body( comments[next_comment].start.lineno )

)

{

print_comment( comments[next_comment] );

assert(curr_pos.lineno <= pos.lineno); // we shouldn't have overshot

}

++next_comment;

}

// Otherwise, just print a blank line

else {

print("\n");

}

auto print_unprinted_comments()

{

for (auto const& c : *pcomments) {

if (!c.dbg_was_printed) {

print_comment(c);

}

// Position ourselves as close to pos as possible,

// and catch up with displaying comments

auto align_to( source_position pos )

-> void

{

auto on_same_line = curr_pos.lineno == pos.lineno;

// Ignoring this logic is used when we're generating new code sections,

// such as return value structs, and emitting raw string literals

if (ignore_align) {

print( pad( ignore_align_indent - curr_pos.colno ) );

return;

}

// Otherwise, we need to apply our usual alignment logic

// Catch up with displaying comments

flush_comments( pos );

// If we're not on the right line

if (

printed_extra

&& !on_same_line

)

{

print_line_directive(pos.lineno);

curr_pos.lineno = pos.lineno;

printed_extra = false;

}

else if (curr_pos.lineno < pos.lineno)

{

// In case we're just one away, try a blank line

// (this might get ignored and we'll get the line directive)

print( "\n" );

if (curr_pos.lineno != pos.lineno) {

print_line_directive(pos.lineno);

}

curr_pos.lineno = pos.lineno;

}

// Finally, align to the target column, if we're on the right line

// and not one-past-the-end on the extra line at section end)

assert(

psource

&& 0 <= curr_pos.lineno

&& curr_pos.lineno < std::ssize(psource->get_lines())+1

);

if (

curr_pos.lineno == pos.lineno

&& curr_pos.lineno < std::ssize(psource->get_lines())

)

{

// Record this line's indentation as the 'last' line for next time

last_line_indentation = psource->get_lines()[curr_pos.lineno].indent();

// If this line was originally densely spaced (had <2 whitespace

// between all tokens), then the programmer likely wasn't doing a lot

// of special formatting...

if (psource->get_lines()[curr_pos.lineno].all_tokens_are_densely_spaced)

{

// For the first token in a line, use the line's original indentation

if (curr_pos.colno <= 1)

{

print( pad( psource->get_lines()[curr_pos.lineno].indent() ) );

}

// For later tokens, don't try to add padding

else {

if (

last_printed_char == ';'

&& on_same_line

)

{

print( " " );

}

// Otherwise, make a best effort to adjust position with some padding

else

{

pos.colno = std::max( 1, pos.colno + pad_for_this_line );

print( pad( pos.colno - curr_pos.colno ) );

}

public:

//-----------------------------------------------------------------------

// Finalize phase

auto finalize_phase(bool print_remaining_comments = false)

{

if (

is_open()

&& psource

&& psource->has_cpp2()

)

{

flush_comments( {curr_pos.lineno+1, 1} );

if (print_remaining_comments) {

print_unprinted_comments();

}

// Always make sure the very last line ends with a newline

// (not really necessary but makes some tools quieter)

// -- but only if there's any Cpp2, otherwise don't

// because passing through all-Cpp1 code should always

// remain diff-identical

if (phase == phase2_func_defs) {

print_extra("\n");

}

//-----------------------------------------------------------------------

// Open

auto open(

std::string const& cpp2_filename_,

std::string const& cpp1_filename_,

std::vector<comment> const& comments,

cpp2::source const& source,

cpp2::parser const& parser

)

-> void

{

cpp2_filename = (flag_line_paths) ?

std::filesystem::absolute(std::filesystem::path(cpp2_filename_)).string() :

cpp2_filename_;

assert(

!is_open()

&& !pcomments

&& "ICE: tried to call .open twice"

);

cpp1_filename = cpp1_filename_;

if (cpp1_filename == "stdout") {

out = &std::cout;

}

else {

out_file.open(cpp1_filename);

out = &out_file;

}

pcomments = &comments;

psource = &source;

pparser = &parser;

}

auto reopen()

-> void

{

assert(

is_open()

&& "ICE: tried to call .reopen without first calling .open"

);

assert(cpp1_filename.ends_with(".h"));

out_file.close();

out_file.open(cpp1_filename + "pp");

}

auto is_open()

-> bool

{

if (out) {

assert(

pcomments

&& "ICE: if is_open, pcomments should also be set"

);

}

return out;

}

//-----------------------------------------------------------------------

// Abandon: close and delete

auto abandon()

-> void

{

if (!is_open()) {

return;

}

if (out_file.is_open()) {

out_file.close();

std::remove(cpp1_filename.c_str());

}

//-----------------------------------------------------------------------

// Print extra text and don't track positions

// Used for Cpp2 boundary comment and prelude and final newline

auto print_extra( std::string_view s )

-> void

{

assert(

is_open()

&& "ICE: printer must be open before printing"

);

print( s, source_position{}, false );

printed_extra = true;

}

//-----------------------------------------------------------------------

// Print a Cpp1 line, which should be at lineno

auto print_cpp1( std::string_view s, lineno_t line )

-> void

{

assert(

is_open()

&& line >= 0

&& "ICE: printer must be open before printing, and line number must not be negative (Cpp1 code is never generated)"

);

// Always start a Cpp1 line on its own new line

ensure_at_start_of_new_line();

// If we are out of sync with the current logical line number,

// emit a #line directive to re-sync

if (curr_pos.lineno != line) {

print_line_directive( line );

curr_pos.lineno = line;

}

// Print the line

assert (curr_pos.colno == 1);

print( s );

print( "\n" );

}

//-----------------------------------------------------------------------

// Used when we start a new Cpp2 section, or when we emit the same item

// more than once (notably when we emit operator= more than once)

auto reset_line_to(lineno_t line, bool force = false)

-> void

{

// Always start a Cpp2 section on its own new line

ensure_at_start_of_new_line();

// If we are out of sync with the current logical line number,

// emit a #line directive to re-sync

if (

force

|| curr_pos.lineno != line

)

{

print_line_directive( line );

curr_pos.lineno = line;

}

assert (curr_pos.colno == 1);

}

//-----------------------------------------------------------------------

// Print a Cpp2 item, which should be at pos

auto print_cpp2(

std::string_view s,

source_position pos,

bool leave_newlines_alone = false,

bool is_known_empty = false

)

-> void

{

// If we're printing for real (not to a string target)

if (emit_target_stack.empty())

{

// If we're in a generated text region (signified by negative

// line numbers), then shunt this call to print_extra instead

if (pos.lineno < 1) {

if (generated_pos_line != pos.lineno) {

*out << "\n" + std::string(last_line_indentation, ' ');

generated_pos_line = pos.lineno;

}

print_extra(s);

return;

}

// Otherwise, we're no longer in generated code, so reset the

// generated code counter

generated_pos_line = {};

}

assert(

is_open()

&& "ICE: printer must be open before printing"

);

// If there are any embedded newlines, split this string into

// separate print_cpp2 calls

if (auto newline_pos = s.find('\n');

!leave_newlines_alone

&& s.length() > 1

&& newline_pos != s.npos

)

{

while (newline_pos != s.npos)

{

// Print the text before the next newline

if (newline_pos > 0) {

print_cpp2( s.substr(0, newline_pos), pos );

}

// Emit the newline as a positioned empty string

assert (s[newline_pos] == '\n');

++pos.lineno;

pos.colno = 1;

print_cpp2( "", pos, false, curr_pos.colno <= 1 );

s.remove_prefix( newline_pos+1 );

newline_pos = s.find('\n');

}

// Print any tail following the last newline

if (!s.empty()) {

print_cpp2( s, pos );

}

return;

}

// The rest of this call handles a single chunk that's either a

// standalone "\n" or a piece of text that doesn't have a newline

// Skip alignment work if we're capturing emitted text

if (emit_target_stack.empty())

{

// Remember where we are

auto last_pos = curr_pos;

// We may want to adjust the position based on (1) a position preemption request

// or else (2) to repeat a similar adjustment we discovered on the previous line

auto adjusted_pos = pos;

// (1) See if there's a position preemption request, if so use it up

// For now, the preempt position use cases are about overriding colno

// and only on the same line. In the future, we might have more use cases.

if (!preempt_pos.empty()) {

if (preempt_pos.back().lineno == pos.lineno) {

adjusted_pos.colno = preempt_pos.back().colno;

}

// (2) Otherwise, see if there's a previous line's offset to repeat

// If we moved to a new line, then this is the first

// non-comment non-whitespace text on the new line

else if (

last_pos.lineno == pos.lineno-1

&& enable_indent_heuristic

)

{

// If the last line had a request for this colno, remember its actual offset

constexpr int sentinel = -100;

auto last_line_offset = sentinel;

for(auto i = 0;

i < std::ssize(prev_line_info.requests)

&& prev_line_info.requests[i].requested <= pos.colno;

++i

)

{

if (prev_line_info.requests[i].requested == pos.colno)

{

last_line_offset = prev_line_info.requests[i].offset;

break;

}

// If there was one, apply the actual column number offset

if (last_line_offset > sentinel) {

adjusted_pos.colno += last_line_offset;

}

enable_indent_heuristic = true;

// If we're changing lines, start accumulating this new line's request/actual adjustment info

if (last_pos.lineno < adjusted_pos.lineno) {

prev_line_info = { curr_pos.lineno, { } };

}

align_to(adjusted_pos);

// Remember the requested and actual offset columns for this item

prev_line_info.requests.push_back( req_act_info( pos.colno /*requested*/ , curr_pos.colno /*actual*/ - pos.colno ) );

}

print(s, pos, true, is_known_empty );

}

//-----------------------------------------------------------------------

// Position override control functions

// Use this position instead of the next supplied one

// Useful when Cpp1 syntax is emitted in a different order/verbosity

// than Cpp2 such as with declarations

auto preempt_position_push(source_position pos)

-> void

{

preempt_pos.push_back( pos );

}

auto preempt_position_pop()

-> void

{

assert(!preempt_pos.empty());

preempt_pos.pop_back();

}

// Add (or, if negative, subtract) padding for the current line only

auto add_pad_in_this_line(colno_t extra)

-> void

{

pad_for_this_line += extra;

}

// Enable indent heuristic for just this line

auto disable_indent_heuristic_for_next_text()

-> void

{

enable_indent_heuristic = false;

}

// Ignore position information, usually when emitting generated code

// such as generated multi-return type structs

auto ignore_alignment(

bool ignore,

int indent = 0

)

-> void

{

// We'll only ever call this in local non-nested true/false pairs.

// If we ever want to generalize (support nesting, or make it non-brittle),

// wrap this in a push/pop stack.

if (ignore) {

ignore_align = true;

ignore_align_indent = indent;

ignore_align_lineno = curr_pos.lineno; // push state

}

else {

ignore_align = false;

ignore_align_indent = 0;

curr_pos.lineno = ignore_align_lineno; // pop state

}

//-----------------------------------------------------------------------

// Modal state control functions

auto next_phase()

-> void

{

inc_phase();

}

// Provide an option to store to a given string instead, which is

// useful for capturing Cpp1-formatted output for generated code

auto emit_to_string( std::string* target = {} )

-> void

{

if (target) {

emit_string_targets.push_back( target );

emit_target_stack.push_back(target_type::string);

}

else {

emit_string_targets.pop_back();

emit_target_stack.pop_back();

}

// Provide an option to store to a vector<text_with_pos>, which is

// useful for postfix expression which have to mix unwrapping operators

// with emitting sub-elements such as expression lists

auto emit_to_text_chunks( std::vector<text_with_pos>* target = {} )

-> void

{

if (target) {

emit_text_chunks_targets.push_back( target );

emit_target_stack.push_back(target_type::chunks);

}

else {

emit_text_chunks_targets.pop_back();

emit_target_stack.pop_back();

}

};

//-----------------------------------------------------------------------

// cppfront: a compiler instance

View remainder of file in raw view

cppfront/source/to_cpp1.h at main · MaxSagebaum/cppfront · GitHub

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