macro_rules - Rework pattern matching to not use try-catch

6 files changed, 1545 insertions, 0 deletions

diff --git a/src/macro_rules/eval.cpp b/src/macro_rules/eval.cpp
new file mode 100644
index 00000000..44900807
--- /dev/null
+++ b/src/macro_rules/eval.cpp
@@ -0,0 +1,639 @@
+/*
+ */
+#include <common.hpp>
+#include "macro_rules.hpp"
+#include <parse/parseerror.hpp>
+#include <parse/tokentree.hpp>
+#include <parse/common.hpp>
+#include <limits.h>
+#include "pattern_checks.hpp"
+
+class ParameterMappings
+{
+    // MultiMap (layer, name) -> TokenTree
+    // - Multiple values are only allowed for layer>0
+    typedef ::std::pair<unsigned, unsigned> t_mapping_block;
+    struct Mapping
+    {
+        t_mapping_block block;
+        ::std::vector<TokenTree>    entries;
+        friend ::std::ostream& operator<<(::std::ostream& os, const Mapping& x) {
+            os << "(" << x.block.first << ", " << x.block.second << "): '" << x.entries << "')";
+            return os;
+        }
+    };
+    
+    struct less_cstr {
+        bool operator()(const char *a, const char *b) const { return ::std::strcmp(a,b) < 0; }
+    };
+    
+    
+    ::std::vector<Mapping>  m_mappings;
+    unsigned m_layer_count;
+    
+    //::std::map<const char*, Mapping*, less_cstr>    m_map;
+    ::std::map<::std::string, Mapping*>    m_map;
+public:
+    ParameterMappings():
+        m_layer_count(0)
+    {
+    }
+    ParameterMappings(ParameterMappings&&) = default;
+    
+    const ::std::vector<Mapping>& mappings() const { return m_mappings; }
+    
+    void dump() const {
+        DEBUG("m_mappings = {" << m_mappings << "}");
+        DEBUG("m_map = {" << m_map << "}");
+    }
+    
+    size_t layer_count() const {
+        return m_layer_count+1;
+    }
+    
+    void insert(unsigned int layer, unsigned int name_index, TokenTree data) {
+        if(layer > m_layer_count)
+            m_layer_count = layer;
+        
+        if( name_index >= m_mappings.size() ) {
+            m_mappings.resize( name_index + 1 );
+        }
+        auto& mapping = m_mappings[name_index];
+        
+        if( mapping.entries.size() == 0 ) {
+            mapping.block.first = layer;
+        }
+        else if( mapping.block.first != layer) {
+            throw ParseError::Generic(FMT("matching argument #'"<<name_index<<"' at multiple layers"));
+        }
+        else {
+        }
+        mapping.entries.push_back( mv$(data) );
+    }
+    
+    void reindex(const ::std::vector< ::std::string>& new_names) {
+        m_map.clear();
+        
+        if( new_names.size() < m_mappings.size() ) {
+            BUG(Span(), "Macro parameter name mismatch - len["<<new_names<<"] != len["<<m_mappings<<"]");
+        }
+        for( unsigned int i = 0; i < m_mappings.size(); i ++ )
+        {
+            m_map.insert( ::std::make_pair(new_names[i].c_str(), &m_mappings[i]) );
+        }
+    }    
+
+    const TokenTree* get(unsigned int layer, unsigned int iteration, const char *name, unsigned int idx) const
+    {
+        const auto it = m_map.find( name );
+        if( it == m_map.end() ) {
+            DEBUG("m_map = " << m_map);
+            return nullptr;
+        }
+        const auto& e = *it->second;
+        if( e.block.first < layer ) {
+            DEBUG(name<<" higher layer (" << e.block.first << ")");
+            return nullptr;
+        }
+        else if( e.block.first > layer ) {
+            throw ParseError::Generic( FMT("'" << name << "' is still repeating at this layer") );
+        }
+        else if( idx >= e.entries.size() ) {
+            DEBUG("Not enough mappings for name " << name << " at layer " << layer << " PI " << iteration);
+            return nullptr;
+        }
+        else {
+            DEBUG(name << " #" << idx << ": " << e.entries[idx]);
+            return &e.entries[idx];
+        }
+    }
+    unsigned int count(unsigned int layer, unsigned int iteration, const char *name) const
+    {
+        const auto it = m_map.find( name );
+        if( it == m_map.end() ) {
+            DEBUG("("<<layer<<","<<iteration<<",'"<<name<<"') not found - m_map={" << m_map << "}");
+            return 0;
+        }
+        const auto& e = *it->second;
+        
+        if( e.block.first < layer ) {
+            DEBUG(name<<" higher layer (" << e.block.first << ")");
+            return UINT_MAX;
+        }
+        else if( e.block.first > layer ) {
+            //throw ParseError::Generic( FMT("'" << name << "' is still repeating at this layer") );
+            // ignore mismatch
+            return UINT_MAX;
+        }
+        else {
+            return e.entries.size();
+        }
+    }
+};
+
+class MacroExpander:
+    public TokenStream
+{
+public:
+
+private:
+    const RcString  m_macro_filename;
+
+    const ::std::string m_crate_name;
+    const ::std::vector<MacroRuleEnt>&  m_root_contents;
+    const ParameterMappings m_mappings;
+    
+
+    struct t_offset {
+        unsigned read_pos;
+        unsigned loop_index;
+        unsigned max_index;
+    };
+    /// Layer states : Index and Iteration
+    ::std::vector< t_offset >   m_offsets;
+    ::std::vector< size_t > m_layer_iters;
+    
+    /// Cached pointer to the current layer
+    const ::std::vector<MacroRuleEnt>*  m_cur_ents;  // For faster lookup.
+
+    Token   m_next_token;   // used for inserting a single token into the stream
+    ::std::unique_ptr<TTStream>   m_ttstream;
+    
+public:
+    MacroExpander(const MacroExpander& x) = delete;
+    //MacroExpander(const MacroExpander& x):
+    //    m_macro_name( x.m_macro_name ),
+    //    m_crate_name(x.m_crate_name),
+    //    m_root_contents(x.m_root_contents),
+    //    m_mappings(x.m_mappings),
+    //    m_offsets({ {0,0,0} }),
+    //    m_cur_ents(&m_root_contents)
+    //{
+    //    prep_counts();
+    //}
+    MacroExpander(const ::std::string& macro_name, const ::std::vector<MacroRuleEnt>& contents, ParameterMappings mappings, ::std::string crate_name):
+        m_macro_filename( FMT("Macro:" << macro_name) ),
+        m_crate_name( mv$(crate_name) ),
+        m_root_contents(contents),
+        m_mappings( mv$(mappings) ),
+        m_offsets({ {0,0,0} }),
+        m_cur_ents(&m_root_contents)
+    {
+        prep_counts();
+    }
+
+    virtual Position getPosition() const override;
+    virtual Token realGetToken() override;
+private:
+    const MacroRuleEnt& getCurLayerEnt() const;
+    const ::std::vector<MacroRuleEnt>* getCurLayer() const;
+    void prep_counts();
+    unsigned int count_repeats(const ::std::vector<MacroRuleEnt>& ents, unsigned layer, unsigned iter);
+};
+
+void Macro_InitDefaults()
+{
+}
+
+bool Macro_TryPattern(TTStream& lex, const MacroPatEnt& pat)
+{
+    DEBUG("pat = " << pat);
+    Token   tok;
+    switch(pat.type)
+    {
+    case MacroPatEnt::PAT_TOKEN: {
+        GET_TOK(tok, lex);
+        bool rv = (tok == pat.tok);
+        PUTBACK(tok, lex);
+        return rv;
+        }
+    case MacroPatEnt::PAT_LOOP:
+        if( pat.name == "*" )
+            return true;
+        return Macro_TryPattern(lex, pat.subpats[0]);
+    case MacroPatEnt::PAT_BLOCK:
+        return LOOK_AHEAD(lex) == TOK_BRACE_OPEN;
+    case MacroPatEnt::PAT_IDENT:
+        return LOOK_AHEAD(lex) == TOK_IDENT;
+    case MacroPatEnt::PAT_TT:
+        return LOOK_AHEAD(lex) != TOK_EOF;
+    case MacroPatEnt::PAT_PATH:
+        return is_token_path( LOOK_AHEAD(lex) );
+    case MacroPatEnt::PAT_TYPE:
+        return is_token_type( LOOK_AHEAD(lex) );
+    case MacroPatEnt::PAT_EXPR:
+        return is_token_expr( LOOK_AHEAD(lex) );
+    case MacroPatEnt::PAT_STMT:
+        return is_token_stmt( LOOK_AHEAD(lex) );
+    case MacroPatEnt::PAT_PAT:
+        return is_token_pat( LOOK_AHEAD(lex) );
+    case MacroPatEnt::PAT_META:
+        return LOOK_AHEAD(lex) == TOK_IDENT;
+    }
+    throw ParseError::Todo(lex, FMT("Macro_TryPattern : " << pat));
+}
+
+bool Macro_HandlePattern(TTStream& lex, const MacroPatEnt& pat, unsigned int layer, ParameterMappings& bound_tts)
+{
+    TRACE_FUNCTION_F("layer = " << layer);
+    Token   tok;
+    TokenTree   val;
+    
+    switch(pat.type)
+    {
+    case MacroPatEnt::PAT_TOKEN:
+        DEBUG("Token " << pat.tok);
+        GET_CHECK_TOK(tok, lex, pat.tok.type());
+        break;
+    case MacroPatEnt::PAT_LOOP:
+    //case MacroPatEnt::PAT_OPTLOOP:
+        {
+        unsigned int match_count = 0;
+        DEBUG("Loop");
+        for(;;)
+        {
+            if( ! Macro_TryPattern(lex, pat.subpats[0]) )
+            {
+                DEBUG("break");
+                break;
+            }
+            for( unsigned int i = 0; i < pat.subpats.size(); i ++ )
+            {
+                if( !Macro_HandlePattern(lex, pat.subpats[i], layer+1, bound_tts) ) {
+                    DEBUG("Ent " << i << " failed");
+                    return false;
+                }
+            }
+            match_count += 1;
+            DEBUG("succ");
+            if( pat.tok.type() != TOK_NULL )
+            {
+                if( GET_TOK(tok, lex) != pat.tok.type() )
+                {
+                    lex.putback( mv$(tok) );
+                    break;
+                }
+            }
+        }
+        DEBUG("Done (" << match_count << " matches)");
+        break; }
+    
+    case MacroPatEnt::PAT_TT:
+        DEBUG("TT");
+        if( GET_TOK(tok, lex) == TOK_EOF )
+            throw ParseError::Unexpected(lex, TOK_EOF);
+        else
+            PUTBACK(tok, lex);
+        val = Parse_TT(lex, false);
+        if(0)
+    case MacroPatEnt::PAT_PAT:
+        val = Parse_TT_Pattern(lex);
+        if(0)
+    case MacroPatEnt::PAT_TYPE:
+        val = Parse_TT_Type(lex);
+        if(0)
+    case MacroPatEnt::PAT_EXPR:
+        val = Parse_TT_Expr(lex);
+        if(0)
+    case MacroPatEnt::PAT_STMT:
+        val = Parse_TT_Stmt(lex);
+        if(0)
+    case MacroPatEnt::PAT_PATH:
+        val = Parse_TT_Path(lex, false);    // non-expr mode
+        if(0)
+    case MacroPatEnt::PAT_BLOCK:
+        val = Parse_TT_Block(lex);
+        if(0)
+    case MacroPatEnt::PAT_META:
+        val = Parse_TT_Meta(lex);
+        if(0)
+    case MacroPatEnt::PAT_IDENT:
+        {
+            GET_CHECK_TOK(tok, lex, TOK_IDENT);
+            val = TokenTree(tok);
+        }
+        bound_tts.insert( layer, pat.name_index, ::std::move(val) );
+        break;
+    
+    //default:
+    //    throw ParseError::Todo("full macro pattern matching");
+    }
+    return true;
+}
+
+::std::unique_ptr<TokenStream> Macro_InvokeRules(const char *name, const MacroRules& rules, const TokenTree& input)
+{
+    TRACE_FUNCTION;
+    
+    const auto* cur_frag = &rules.m_pattern;
+    unsigned int    cur_frag_ofs = 0;
+    
+    ParameterMappings   bound_tts;
+    unsigned int    rule_index;
+    
+    TTStream    lex(input);
+    while(true)
+    {
+        // If not at the end of the fragment, handle that pattern
+        if( cur_frag_ofs < cur_frag->m_pats_ents.size() )
+        {
+            const auto& pat = cur_frag->m_pats_ents[cur_frag_ofs];
+            DEBUG("- try " << pat);
+            if( !Macro_HandlePattern(lex, pat, 0, bound_tts) )
+                throw ParseError::Generic(lex, "Macro pattern failed");
+            // Keep going
+            cur_frag_ofs ++;
+        }
+        else
+        {
+            // The stream has ended
+            if( LOOK_AHEAD(lex) == TOK_EOF ) {
+                // Check if an end is expected here
+                if( cur_frag->m_pattern_end == ~0u ) {
+                    Token   tok = lex.getToken();
+                    ERROR(tok.get_pos(), E0000, "Unexpected end of macro invocation - " << cur_frag_ofs << " != len [" << cur_frag->m_pats_ents << "]");
+                }
+                // We've found the rule!
+                rule_index = cur_frag->m_pattern_end;
+                break;
+            }
+            
+            // Search for which path to take
+            for(const auto& next : cur_frag->m_next_frags) {
+                assert(next.m_pats_ents.size() > 0);
+                if( Macro_TryPattern(lex, next.m_pats_ents.front()) ) {
+                    cur_frag = &next;
+                    cur_frag_ofs = 0;
+                    goto continue_;
+                }
+            }
+            
+            // No paths matched - error out
+            {
+                ::std::stringstream expected;
+                for(const auto& next : cur_frag->m_next_frags) {
+                    expected << next.m_pats_ents.front() << ", ";
+                }
+                
+                Token   tok = lex.getToken();
+                ERROR(tok.get_pos(), E0000, "Unexpected token in macro invocation - " << tok << " - expected " << expected.str());
+            }
+            
+        continue_:
+            (void)0;
+        }
+    }
+    
+    const auto& rule = rules.m_rules[rule_index];
+    
+    DEBUG( rule.m_contents.size() << " rule contents bound to " << bound_tts.mappings().size() << " values - " << name );
+    bound_tts.reindex( rule.m_param_names );
+    for( unsigned int i = 0; i < bound_tts.mappings().size(); i ++ )
+    {
+        DEBUG(" - " << rule.m_param_names[i] << " = [" << bound_tts.mappings()[i] << "]");
+    }
+    bound_tts.dump();
+    
+    DEBUG("TODO: Obtain crate name correctly");
+    TokenStream* ret_ptr = new MacroExpander(name, rule.m_contents, mv$(bound_tts), "");
+    // HACK! Disable nested macro expansion
+    //ret_ptr->parse_state().no_expand_macros = true;
+    
+    return ::std::unique_ptr<TokenStream>( ret_ptr );
+}
+
+
+Position MacroExpander::getPosition() const
+{
+    return Position(m_macro_filename, 0, m_offsets[0].read_pos);
+}
+Token MacroExpander::realGetToken()
+{
+    // Use m_next_token first
+    if( m_next_token.type() != TOK_NULL )
+    {
+        DEBUG("m_next_token = " << m_next_token);
+        return ::std::move(m_next_token);
+    }
+    // Then try m_ttstream
+    if( m_ttstream.get() )
+    {
+        DEBUG("TTStream set");
+        Token rv = m_ttstream->getToken();
+        if( rv.type() != TOK_EOF )
+            return rv;
+        m_ttstream.reset();
+    }
+    //DEBUG("ofs " << m_offsets << " < " << m_root_contents.size());
+    
+    // Check offset of lowest layer
+    while(m_offsets.size() > 0)
+    {
+        unsigned int layer = m_offsets.size() - 1;
+        const auto& ents = *m_cur_ents;
+        
+        // Obtain current read position in layer, and increment
+        size_t idx = m_offsets.back().read_pos++;
+        
+        // Check if limit has been reached
+        if( idx < ents.size() )
+        {
+            // - If not, just handle the next entry
+            const auto& ent = ents[idx];
+            // Check type of entry
+            // - XXX: Hack for $crate special name
+            if( ent.name == "*crate" )
+            {
+                DEBUG("Crate name hack");
+                if( m_crate_name != "" )
+                {
+                    m_next_token = Token(TOK_STRING, m_crate_name);
+                    return Token(TOK_DOUBLE_COLON);
+                }
+            }
+            // - Expand to a parameter
+            else if( ent.name != "" )
+            {
+                DEBUG("lookup '" << ent.name << "'");
+                const TokenTree* tt;
+                unsigned int search_layer = layer;
+                do {
+                    unsigned int parent_iter = (search_layer > 0 ? m_layer_iters.at(search_layer-1) : 0);
+                    const size_t iter_idx = m_offsets.at(search_layer).loop_index;
+                    tt = m_mappings.get(search_layer, parent_iter, ent.name.c_str(), iter_idx);
+                } while( !tt && search_layer-- > 0 );
+                if( ! tt )
+                {
+                    throw ParseError::Generic(*this, FMT("Cannot find '" << ent.name << "' for " << layer));
+                }
+                else
+                {
+                    m_ttstream.reset( new TTStream(*tt) );
+                    return m_ttstream->getToken();
+                }
+            }
+            // - Descend into a repetition
+            else if( ent.subpats.size() != 0 )
+            {
+                DEBUG("desc: layer = " << layer << ", m_layer_iters = " << m_layer_iters);
+                unsigned int layer_iter = m_layer_iters.at(layer);
+                unsigned int num_repeats = this->count_repeats(ent.subpats, layer+1, layer_iter);
+                if(num_repeats == UINT_MAX)
+                    num_repeats = 0;
+                // New layer
+                DEBUG("- NL = " << layer+1 << ", count = " << num_repeats );
+                if( num_repeats > 0 )
+                {
+                    // - Push an offset
+                    m_offsets.push_back( {0, 0, num_repeats} );
+                    // - Save the current layer
+                    m_cur_ents = getCurLayer();
+                    // - Restart loop for new layer
+                }
+                else
+                {
+                    // Layer empty
+                    DEBUG("Layer " << layer+1 << " is empty");
+                }
+                // VVV fall through and continue loop
+            }
+            // - Emit a raw token
+            else
+            {
+                return ent.tok;
+            }
+            // Fall through for loop
+        }
+        else if( layer > 0 )
+        {
+            // - Otherwise, restart/end loop and fall through
+            DEBUG("layer = " << layer << ", m_layer_iters = " << m_layer_iters);
+            auto& cur_ofs = m_offsets.back();
+            DEBUG("Layer #" << layer << " Cur: " << cur_ofs.loop_index << ", Max: " << cur_ofs.max_index);
+            if( cur_ofs.loop_index + 1 < cur_ofs.max_index )
+            {
+                m_layer_iters.at(layer) ++;
+                
+                DEBUG("Restart layer");
+                cur_ofs.read_pos = 0;
+                cur_ofs.loop_index ++;
+                
+                auto& loop_layer = getCurLayerEnt();
+                assert(loop_layer.subpats.size());
+                if( loop_layer.tok.type() != TOK_NULL ) {
+                    DEBUG("- Separator token = " << loop_layer.tok);
+                    return loop_layer.tok;
+                }
+                // Fall through and restart layer
+            }
+            else
+            {
+                DEBUG("Terminate layer");
+                // Terminate loop, fall through to lower layers
+                m_offsets.pop_back();
+                // - Special case: End of macro, avoid issues
+                if( m_offsets.size() == 0 )
+                    break;
+                m_cur_ents = getCurLayer();
+            }
+        }
+        else
+        {
+            DEBUG("Terminate evaluation");
+            m_offsets.pop_back();
+            assert( m_offsets.size() == 0 );
+        }
+    } // while( m_offsets NONEMPTY )
+    
+    DEBUG("EOF");
+    return Token(TOK_EOF);
+}
+
+/// Count the number of names at each layer
+void MacroExpander::prep_counts()
+{
+    m_layer_iters.resize(m_mappings.layer_count(), 0);
+}
+const MacroRuleEnt& MacroExpander::getCurLayerEnt() const
+{
+    assert( m_offsets.size() > 1 );
+    
+    const ::std::vector<MacroRuleEnt>* ents = &m_root_contents;
+    for( unsigned int i = 0; i < m_offsets.size()-2; i ++ )
+    {
+        unsigned int ofs = m_offsets[i].read_pos;
+        assert( ofs > 0 && ofs <= ents->size() );
+        ents = &(*ents)[ofs-1].subpats;
+    }
+    return (*ents)[m_offsets[m_offsets.size()-2].read_pos-1];
+    
+}
+const ::std::vector<MacroRuleEnt>* MacroExpander::getCurLayer() const
+{
+    assert( m_offsets.size() > 0 );
+    const ::std::vector<MacroRuleEnt>* ents = &m_root_contents;
+    for( unsigned int i = 0; i < m_offsets.size()-1; i ++ )
+    {
+        unsigned int ofs = m_offsets[i].read_pos;
+        //DEBUG(i << " ofs=" << ofs << " / " << ents->size());
+        assert( ofs > 0 && ofs <= ents->size() );
+        ents = &(*ents)[ofs-1].subpats;
+        //DEBUG("ents = " << ents);
+    }
+    return ents;
+}
+unsigned int MacroExpander::count_repeats(const ::std::vector<MacroRuleEnt>& ents, unsigned layer, unsigned iter)
+{
+    bool    valid = false;
+    unsigned int count = 0;
+    for(const auto& ent : ents)
+    {
+        if( ent.name != "" )
+        {
+            if( ent.name[0] == '*' ) {
+                // Ignore meta-vars, they don't repeat
+            }
+            else {
+                auto c = m_mappings.count(layer, iter, ent.name.c_str());
+                DEBUG(c << " mappings for " << ent.name << " at (" << layer << ", " << iter << ")");
+                if( c == UINT_MAX ) {
+                    // Ignore
+                }
+                else if(!valid || count == c) {
+                    count = c;
+                    valid = true;
+                }
+                else {
+                    // Mismatch!
+                    throw ParseError::Generic("count_repeats - iteration count mismatch");
+                }
+            }
+        }
+        else if( ent.subpats.size() > 0 )
+        {
+            auto c = this->count_repeats(ent.subpats, layer, iter);
+            if( c == UINT_MAX ) {
+            }
+            else if(!valid || count == c) {
+                count = c;
+                valid = true;
+            }
+            else {
+                // Mismatch!
+                throw ParseError::Generic("count_repeats - iteration count mismatch (subpat)");
+            }
+        }
+        else
+        {
+            // Don't care
+        }
+    }
+    
+    if(valid) {
+        return count;
+    }
+    else {
+        return UINT_MAX;
+    }
+}
+
diff --git a/src/macro_rules/macro_rules.hpp b/src/macro_rules/macro_rules.hpp
new file mode 100644
index 00000000..65822fa5
--- /dev/null
+++ b/src/macro_rules/macro_rules.hpp
@@ -0,0 +1,153 @@
+#ifndef MACROS_HPP_INCLUDED

+#define MACROS_HPP_INCLUDED

+

+#include "parse/lex.hpp"

+#include "parse/tokentree.hpp"

+#include <common.hpp>

+#include <map>

+#include <memory>

+#include <cstring>

+#include "macro_rules_ptr.hpp"

+

+class MacroExpander;

+

+class MacroRuleEnt:

+    public Serialisable

+{

+    friend class MacroExpander;

+

+    Token   tok;

+    ::std::string   name;

+    ::std::vector<MacroRuleEnt> subpats;

+public:

+    MacroRuleEnt():

+        tok(TOK_NULL),

+        name("")

+    {

+    }

+    MacroRuleEnt(Token tok):

+        tok( mv$(tok) ),

+        name("")

+    {

+    }

+    MacroRuleEnt(::std::string name):

+        name( mv$(name) )

+    {

+    }

+    MacroRuleEnt(Token tok, ::std::vector<MacroRuleEnt> subpats):

+        tok( mv$(tok) ),

+        subpats( mv$(subpats) )

+    {

+    }

+

+    friend ::std::ostream& operator<<(::std::ostream& os, const MacroRuleEnt& x);

+

+    SERIALISABLE_PROTOTYPES();

+};

+struct MacroPatEnt:

+    public Serialisable

+{

+    ::std::string   name;

+    unsigned int    name_index;

+    Token   tok;

+    

+    ::std::vector<MacroPatEnt>  subpats;

+    

+    enum Type {

+        PAT_TOKEN,  // A token

+        PAT_LOOP,   // $() Enables use of subpats

+        

+        PAT_TT, // :tt

+        PAT_PAT,    // :pat

+        PAT_IDENT,

+        PAT_PATH,

+        PAT_TYPE,

+        PAT_EXPR,

+        PAT_STMT,

+        PAT_BLOCK,

+        PAT_META,

+    } type;

+

+    MacroPatEnt():

+        tok(TOK_NULL),

+        type(PAT_TOKEN)

+    {

+    }

+    MacroPatEnt(Token tok):

+        tok( mv$(tok) ),

+        type(PAT_TOKEN)

+    {

+    }

+    

+    MacroPatEnt(::std::string name, unsigned int name_index, Type type):

+        name( mv$(name) ),

+        name_index( name_index ),

+        tok(),

+        type(type)

+    {

+    }

+    

+    MacroPatEnt(Token sep, bool need_once, ::std::vector<MacroPatEnt> ents):

+        name( need_once ? "+" : "*" ),

+        tok( mv$(sep) ),

+        subpats( move(ents) ),

+        type(PAT_LOOP)

+    {

+    }

+

+    friend ::std::ostream& operator<<(::std::ostream& os, const MacroPatEnt& x);

+    

+    SERIALISABLE_PROTOTYPES();

+};

+

+struct MacroRulesPatFrag:

+    public Serialisable

+{

+    ::std::vector<MacroPatEnt>  m_pats_ents;

+    unsigned int    m_pattern_end;

+    ::std::vector< MacroRulesPatFrag >  m_next_frags;

+    

+    MacroRulesPatFrag():

+        m_pattern_end(~0)

+    {}

+    

+    SERIALISABLE_PROTOTYPES();

+};

+

+/// An arm within a macro_rules! blcok

+struct MacroRulesArm:

+    public Serialisable

+{

+    ::std::vector< ::std::string>   m_param_names;

+    ::std::vector<MacroRuleEnt> m_contents;

+    

+    MacroRulesArm()

+    {}

+    MacroRulesArm(::std::vector<MacroRuleEnt> contents):

+        m_contents( mv$(contents) )

+    {}

+    

+    SERIALISABLE_PROTOTYPES();

+};

+

+/// A sigle 'macro_rules!' block

+class MacroRules:

+    public Serialisable

+{

+public:

+    bool m_exported;

+    MacroRulesPatFrag  m_pattern;

+    ::std::vector<MacroRulesArm>  m_rules;

+    

+    MacroRules()

+    {

+    }

+    virtual ~MacroRules();

+    

+    SERIALISABLE_PROTOTYPES();

+};

+

+extern ::std::unique_ptr<TokenStream>   Macro_InvokeRules(const char *name, const MacroRules& rules, const TokenTree& input);

+extern MacroRulesPtr    Parse_MacroRules(TokenStream& lex);

+

+#endif // MACROS_HPP_INCLUDED

diff --git a/src/macro_rules/macro_rules_ptr.hpp b/src/macro_rules/macro_rules_ptr.hpp
new file mode 100644
index 00000000..512cbda2
--- /dev/null
+++ b/src/macro_rules/macro_rules_ptr.hpp
@@ -0,0 +1,31 @@
+/*
+ */
+#pragma once
+
+class MacroRules;
+
+class MacroRulesPtr:
+    public Serialisable
+{
+    MacroRules* m_ptr;
+public:
+    MacroRulesPtr() {}
+    MacroRulesPtr(MacroRules* p): m_ptr(p) {}
+    MacroRulesPtr(MacroRulesPtr&& x):
+        m_ptr(x.m_ptr)
+    {
+        x.m_ptr = nullptr;
+    }
+    MacroRulesPtr& operator=(MacroRulesPtr&& x)
+    {
+        m_ptr = x.m_ptr; x.m_ptr = nullptr;
+        return *this;
+    }
+    
+    ~MacroRulesPtr();
+    
+          MacroRules& operator*()       { assert(m_ptr); return *m_ptr; }
+    const MacroRules& operator*() const { assert(m_ptr); return *m_ptr; }
+    
+    SERIALISABLE_PROTOTYPES();
+};
diff --git a/src/macro_rules/mod.cpp b/src/macro_rules/mod.cpp
new file mode 100644
index 00000000..e3699a3d
--- /dev/null
+++ b/src/macro_rules/mod.cpp
@@ -0,0 +1,203 @@
+/*

+ */

+#include <common.hpp>

+#include "macro_rules.hpp"

+#include <parse/parseerror.hpp>

+#include <parse/tokentree.hpp>

+#include <parse/common.hpp>

+#include <limits.h>

+

+#include "pattern_checks.hpp"

+

+bool is_token_path(eTokenType tt) {

+    switch(tt)

+    {

+    case TOK_IDENT:

+    case TOK_DOUBLE_COLON:

+    case TOK_LT:

+    case TOK_DOUBLE_LT:

+    case TOK_RWORD_SELF:

+    case TOK_RWORD_SUPER:

+        return true;

+    default:

+        return false;

+    }

+}

+bool is_token_pat(eTokenType tt) {

+    if( is_token_path(tt) )

+        return true;

+    switch( tt )

+    {

+    case TOK_PAREN_OPEN:

+    case TOK_SQUARE_OPEN:

+    

+    case TOK_AMP:

+    case TOK_RWORD_BOX:

+    case TOK_RWORD_REF:

+    case TOK_RWORD_MUT:

+    case TOK_STRING:

+    case TOK_INTEGER:

+    case TOK_CHAR:

+        return true;

+    default:

+        return false;

+    }

+}

+bool is_token_type(eTokenType tt) {

+    if( is_token_path(tt) )

+        return true;

+    switch( tt )

+    {

+    case TOK_PAREN_OPEN:

+    case TOK_SQUARE_OPEN:

+    case TOK_STAR:

+    case TOK_AMP:

+        return true;

+    default:

+        return false;

+    }

+}

+bool is_token_expr(eTokenType tt) {

+    if( is_token_path(tt) )

+        return true;

+    switch( tt )

+    {

+    case TOK_AMP:

+    case TOK_STAR:

+    case TOK_PAREN_OPEN:

+    case TOK_MACRO:

+    case TOK_DASH:

+    

+    case TOK_INTEGER:

+    case TOK_STRING:

+        return true;

+    default:

+        return false;

+    }

+}

+bool is_token_stmt(eTokenType tt) {

+    if( is_token_expr(tt) )

+        return true;

+    switch( tt )

+    {

+    case TOK_BRACE_OPEN:

+    case TOK_RWORD_LET:

+        return true;

+    default:

+        return false;

+    }

+}

+

+MacroRulesPtr::~MacroRulesPtr()

+{

+    if(m_ptr)

+    {

+        delete m_ptr;

+        m_ptr = nullptr;

+    }

+}

+SERIALISE_TYPE(MacroRulesPtr::, "MacroRulesPtr", {

+},{

+})

+

+SERIALISE_TYPE_S(MacroRulesArm, {

+})

+SERIALISE_TYPE_S(MacroRulesPatFrag, {

+})

+

+void operator%(Serialiser& s, MacroPatEnt::Type c) {

+    switch(c) {

+    #define _(v) case MacroPatEnt::v: s << #v; return

+    _(PAT_TOKEN);

+    _(PAT_TT);

+    _(PAT_PAT);

+    _(PAT_TYPE);

+    _(PAT_EXPR);

+    _(PAT_LOOP);

+    _(PAT_STMT);

+    _(PAT_PATH);

+    _(PAT_BLOCK);

+    _(PAT_META);

+    _(PAT_IDENT);

+    #undef _

+    }

+}

+void operator%(::Deserialiser& s, MacroPatEnt::Type& c) {

+    ::std::string   n;

+    s.item(n);

+    #define _(v) else if(n == #v) c = MacroPatEnt::v

+    if(0) ;

+    _(PAT_TOKEN);

+    _(PAT_TT);

+    _(PAT_PAT);

+    _(PAT_TYPE);

+    _(PAT_EXPR);

+    _(PAT_LOOP);

+    //_(PAT_OPTLOOP);

+    _(PAT_STMT);

+    _(PAT_PATH);

+    _(PAT_BLOCK);

+    _(PAT_META);

+    _(PAT_IDENT);

+    else

+        throw ::std::runtime_error( FMT("No conversion for '" << n << "'") );

+    #undef _

+}

+SERIALISE_TYPE_S(MacroPatEnt, {

+    s % type;

+    s.item(name);

+    s.item(tok);

+    s.item(subpats);

+});

+::std::ostream& operator<<(::std::ostream& os, const MacroPatEnt& x)

+{

+    switch(x.type)

+    {

+    case MacroPatEnt::PAT_TOKEN: os << "=" << x.tok; break;

+    case MacroPatEnt::PAT_LOOP:  os << "loop w/ "  << x.tok << " [" << x.subpats << "]";  break;

+    default:

+        os << "$" << x.name << ":";

+        switch(x.type)

+        {

+        case MacroPatEnt::PAT_TOKEN: throw "";

+        case MacroPatEnt::PAT_LOOP:  throw "";

+        case MacroPatEnt::PAT_TT:    os << "tt";    break;

+        case MacroPatEnt::PAT_PAT:   os << "pat";   break;

+        case MacroPatEnt::PAT_IDENT: os << "ident"; break;

+        case MacroPatEnt::PAT_PATH:  os << "path";  break;

+        case MacroPatEnt::PAT_TYPE:  os << "type";  break;

+        case MacroPatEnt::PAT_EXPR:  os << "expr";  break;

+        case MacroPatEnt::PAT_STMT:  os << "stmt";  break;

+        case MacroPatEnt::PAT_BLOCK: os << "block"; break;

+        case MacroPatEnt::PAT_META:  os << "meta"; break;

+        }

+        break;

+    }

+    return os;

+}

+

+SERIALISE_TYPE_S(MacroRuleEnt, {

+    s.item(name);

+    s.item(tok);

+    s.item(subpats);

+});

+

+::std::ostream& operator<<(::std::ostream& os, const MacroRuleEnt& x)

+{

+    if(x.name.size())

+        os << "$"<<x.name;

+    else if( x.subpats.size() )

+        os << "expand w/ " << x.tok << " [" << x.subpats << "]";

+    else

+        os << "=" << x.tok;

+    return os;

+}

+

+MacroRules::~MacroRules()

+{

+}

+SERIALISE_TYPE_S(MacroRules, {

+    s.item( m_exported );

+    s.item( m_rules );

+});

+

diff --git a/src/macro_rules/parse.cpp b/src/macro_rules/parse.cpp
new file mode 100644
index 00000000..2d8ad374
--- /dev/null
+++ b/src/macro_rules/parse.cpp
@@ -0,0 +1,509 @@
+/*
+ */
+#include <common.hpp>
+#include "../parse/common.hpp"
+#include "../parse/parseerror.hpp"
+#include "macro_rules.hpp"
+#include "pattern_checks.hpp"
+
+MacroRulesPtr Parse_MacroRules(TokenStream& lex);
+
+/// A rule within a macro_rules! blcok
+class MacroRule
+{
+public:
+    ::std::vector<MacroPatEnt>  m_pattern;
+    ::std::vector<MacroRuleEnt> m_contents;
+};
+
+::std::vector<MacroPatEnt> Parse_MacroRules_Pat(TokenStream& lex, bool allow_sub, enum eTokenType open, enum eTokenType close,  ::std::vector< ::std::string>& names)
+{
+    TRACE_FUNCTION;
+    Token tok;
+    
+    ::std::vector<MacroPatEnt>  ret;
+    
+     int    depth = 0;
+    while( GET_TOK(tok, lex) != close || depth > 0 )
+    {
+        if( tok.type() == open )
+        {
+            depth ++;
+        }
+        else if( tok.type() == close )
+        {
+            if(depth == 0)
+                throw ParseError::Generic(FMT("Unmatched " << Token(close) << " in macro pattern"));
+            depth --;
+        }
+        
+        switch(tok.type())
+        {
+        case TOK_DOLLAR:
+            switch( GET_TOK(tok, lex) )
+            {
+            case TOK_IDENT: {
+                ::std::string   name = tok.str();
+                GET_CHECK_TOK(tok, lex, TOK_COLON);
+                GET_CHECK_TOK(tok, lex, TOK_IDENT);
+                ::std::string   type = tok.str();
+                
+                unsigned int idx = ::std::find( names.begin(), names.end(), name ) - names.begin();
+                if( idx == names.size() )
+                    names.push_back( name );
+                
+                if(0)
+                    ;
+                else if( type == "tt" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_TT) );
+                else if( type == "pat" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_PAT) );
+                else if( type == "ident" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_IDENT) );
+                else if( type == "path" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_PATH) );
+                else if( type == "expr" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_EXPR) );
+                else if( type == "ty" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_TYPE) );
+                else if( type == "meta" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_META) );
+                else if( type == "block" )
+                    ret.push_back( MacroPatEnt(name, idx, MacroPatEnt::PAT_BLOCK) );
+                else
+                    throw ParseError::Generic(lex, FMT("Unknown fragment type '" << type << "'"));
+                break; }
+            case TOK_PAREN_OPEN:
+                if( allow_sub )
+                {
+                    auto subpat = Parse_MacroRules_Pat(lex, true, TOK_PAREN_OPEN, TOK_PAREN_CLOSE, names);
+                    enum eTokenType joiner = TOK_NULL;
+                    GET_TOK(tok, lex);
+                    if( tok.type() != TOK_PLUS && tok.type() != TOK_STAR )
+                    {
+                        DEBUG("Joiner = " << tok);
+                        joiner = tok.type();
+                        GET_TOK(tok, lex);
+                    }
+                    DEBUG("tok = " << tok);
+                    switch(tok.type())
+                    {
+                    case TOK_PLUS:
+                        DEBUG("$()+ " << subpat);
+                        ret.push_back( MacroPatEnt(Token(joiner), true, ::std::move(subpat)) );
+                        break;
+                    case TOK_STAR:
+                        DEBUG("$()* " << subpat);
+                        ret.push_back( MacroPatEnt(Token(joiner), false, ::std::move(subpat)) );
+                        break;
+                    default:
+                        throw ParseError::Unexpected(lex, tok);
+                    }
+                }
+                else
+                {
+                    throw ParseError::Generic(lex, FMT("Nested repetitions in macro"));
+                }
+                break;
+            default:
+                throw ParseError::Unexpected(lex, tok);
+            }
+            break;
+        case TOK_EOF:
+            throw ParseError::Unexpected(lex, tok);
+        default:
+            ret.push_back( MacroPatEnt(tok) );
+            break;
+        }
+    }
+    
+    return ret;
+}
+
+::std::vector<MacroRuleEnt> Parse_MacroRules_Cont(TokenStream& lex, bool allow_sub, enum eTokenType open, enum eTokenType close)
+{
+    TRACE_FUNCTION;
+    
+    Token tok;
+    ::std::vector<MacroRuleEnt> ret;
+    
+     int    depth = 0;
+    while( GET_TOK(tok, lex) != close || depth > 0 )
+    {
+        if( tok.type() == TOK_EOF ) {
+            throw ParseError::Unexpected(lex, tok);
+        }
+        if( tok.type() == TOK_NULL )    continue ;
+        
+        if( tok.type() == open )
+        {
+            DEBUG("depth++");
+            depth ++;
+        }
+        else if( tok.type() == close )
+        {
+            DEBUG("depth--");
+            if(depth == 0)
+                throw ParseError::Generic(FMT("Unmatched " << Token(close) << " in macro content"));
+            depth --;
+        }
+        
+        if( tok.type() == TOK_DOLLAR )
+        {
+            GET_TOK(tok, lex);
+            
+            if( tok.type() == TOK_PAREN_OPEN )
+            {   
+                if( !allow_sub )
+                    throw ParseError::Unexpected(lex, tok);
+                
+                auto content = Parse_MacroRules_Cont(lex, true, TOK_PAREN_OPEN, TOK_PAREN_CLOSE);
+                
+                GET_TOK(tok, lex);
+                enum eTokenType joiner = TOK_NULL;
+                if( tok.type() != TOK_PLUS && tok.type() != TOK_STAR )
+                {
+                    joiner = tok.type();
+                    GET_TOK(tok, lex);
+                }
+                DEBUG("joiner = " << Token(joiner) << ", content = " << content);
+                switch(tok.type())
+                {
+                case TOK_STAR:
+                    ret.push_back( MacroRuleEnt(joiner, ::std::move(content)) );
+                    break;
+                case TOK_PLUS:
+                    // TODO: Ensure that the plusses match
+                    ret.push_back( MacroRuleEnt(joiner, ::std::move(content)) );
+                    break;
+                default:
+                    throw ParseError::Unexpected(lex, tok);
+                }
+                
+            }
+            else if( tok.type() == TOK_IDENT )
+            {
+                ret.push_back( MacroRuleEnt(tok.str()) );
+            }
+            else if( tok.type() == TOK_RWORD_CRATE )
+            {
+                ret.push_back( MacroRuleEnt("*crate") );
+            }
+            else
+            {
+                throw ParseError::Unexpected(lex, tok);
+            }
+        }
+        else
+        {
+            ret.push_back( MacroRuleEnt(tok) );
+        }
+    }
+    
+    return ret;
+}
+
+MacroRule Parse_MacroRules_Var(TokenStream& lex)
+{
+    TRACE_FUNCTION;
+    Token tok;
+    
+    MacroRule   rule;
+    
+    // Pattern
+    enum eTokenType close;
+    switch(GET_TOK(tok, lex))
+    {
+    case TOK_BRACE_OPEN:    close = TOK_BRACE_CLOSE;    break;
+    case TOK_PAREN_OPEN:    close = TOK_PAREN_CLOSE;    break;
+    default:
+        throw ParseError::Unexpected(lex, tok);
+    }
+    // - Pattern entries
+    ::std::vector< ::std::string>   names;
+    rule.m_pattern = Parse_MacroRules_Pat(lex, true, tok.type(), close,  names);
+    
+    GET_CHECK_TOK(tok, lex, TOK_FATARROW);
+
+    // Replacement
+    switch(GET_TOK(tok, lex))
+    {
+    case TOK_BRACE_OPEN:    close = TOK_BRACE_CLOSE;    break;
+    case TOK_PAREN_OPEN:    close = TOK_PAREN_CLOSE;    break;
+    default:
+        throw ParseError::Unexpected(lex, tok);
+    }
+    rule.m_contents = Parse_MacroRules_Cont(lex, true, tok.type(), close);
+
+    DEBUG("Rule - ["<<rule.m_pattern<<"] => "<<rule.m_contents<<"");
+    
+    return rule;
+}
+
+bool patterns_are_same(const Span& sp, const MacroPatEnt& left, const MacroPatEnt& right)
+{
+    if( left.type > right.type )
+        return patterns_are_same(sp, right, left);
+    
+    //if( left.name != right.name ) {
+    //    TODO(sp, "Handle different binding names " << left << " != " << right);
+    //}
+    
+    // NOTE: left.type <= right.type
+    switch(right.type)
+    {
+    case MacroPatEnt::PAT_TOKEN:
+        assert( left.type == MacroPatEnt::PAT_TOKEN );
+        return right.tok == left.tok;
+    case MacroPatEnt::PAT_LOOP:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            // - Check for compatibility, but these two don't match
+            if( patterns_are_same(sp, left, right.subpats.at(0)) == true )
+                ERROR(sp, E0000, "Incompatible use of loop with matching non-loop");
+            return false;
+        case MacroPatEnt::PAT_LOOP:
+            TODO(sp, "patterns_are_same - PAT_LOOP");
+        default:
+            assert( !"" );
+        }
+    
+    case MacroPatEnt::PAT_TT:
+        if( left.type == right.type )
+            return true;
+        ERROR(sp, E0000, "Incompatible macro fragments - " << right << " used with " << left);
+        break;
+    
+    case MacroPatEnt::PAT_PAT:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            // - If this token is a valid pattern token, error
+            if( is_token_pat(left.tok.type()) )
+                ERROR(sp, E0000, "Incompatible macro fragments - " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_PAT:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments - " << right << " used with " << left);
+        }
+        break;
+    // `:ident` - Compatible with just other tokens
+    case MacroPatEnt::PAT_IDENT:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( left.tok.type() == TOK_IDENT )
+                ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_IDENT:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    case MacroPatEnt::PAT_PATH:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( is_token_path(left.tok.type()) )
+                ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_PATH:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    case MacroPatEnt::PAT_TYPE:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( is_token_type(left.tok.type()) )
+                ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_TYPE:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    case MacroPatEnt::PAT_EXPR:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( is_token_expr(left.tok.type()) )
+                ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_EXPR:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    case MacroPatEnt::PAT_STMT:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( is_token_stmt(left.tok.type()) )
+                ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+            return false;
+        case MacroPatEnt::PAT_STMT:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    // Block - Expects '{' - Compatible with everything but a literal '{'
+    case MacroPatEnt::PAT_BLOCK:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( left.tok.type() == TOK_BRACE_OPEN )
+                ERROR(sp, E0000, "Incompatible macro fragments");
+            return false;
+        case MacroPatEnt::PAT_BLOCK:
+            return true;
+        default:
+            return false;
+        }
+    // Matches meta/attribute fragments.
+    case MacroPatEnt::PAT_META:
+        switch(left.type)
+        {
+        case MacroPatEnt::PAT_TOKEN:
+            if( left.tok.type() == TOK_IDENT )
+                ERROR(sp, E0000, "Incompatible macro fragments");
+            return false;
+        case MacroPatEnt::PAT_META:
+            return true;
+        default:
+            ERROR(sp, E0000, "Incompatible macro fragments " << right << " used with " << left);
+        }
+    }
+    throw "";
+}
+
+MacroRulesPatFrag split_fragment_at(MacroRulesPatFrag& frag, unsigned int remaining_count)
+{
+    MacroRulesPatFrag   rv;
+    for(unsigned int i = remaining_count; i < frag.m_pats_ents.size(); i ++)
+        rv.m_pats_ents.push_back( mv$(frag.m_pats_ents[i]) );
+    frag.m_pats_ents.resize(remaining_count);
+    rv.m_pattern_end = frag.m_pattern_end;   frag.m_pattern_end = ~0;
+    rv.m_next_frags = mv$(frag.m_next_frags);
+    return rv;
+}
+
+void enumerate_names(const ::std::vector<MacroPatEnt>& pats, ::std::vector< ::std::string>& names) {
+    for( const auto& pat : pats )
+    {
+        if( pat.type == MacroPatEnt::PAT_LOOP ) {
+            enumerate_names(pat.subpats, names);
+        }
+        else if( pat.name != "" ) {
+            auto b = names.begin();
+            auto e = names.end();
+            if( ::std::find(b, e, pat.name) == e ) {
+                names.push_back( pat.name );
+            }
+        }
+    }
+}
+
+MacroRulesPtr Parse_MacroRules(TokenStream& lex)
+{
+    TRACE_FUNCTION_F("");
+    
+    Token tok;
+    
+    // Parse the patterns and replacements
+    ::std::vector<MacroRule>    rules;
+    while( GET_TOK(tok, lex) != TOK_EOF )
+    {
+        lex.putback(tok);
+        
+        rules.push_back( Parse_MacroRules_Var(lex) );
+        if(GET_TOK(tok, lex) != TOK_SEMICOLON) {
+            CHECK_TOK(tok, TOK_EOF);
+            break;
+        }
+    }
+    
+    MacroRulesPatFrag   root_frag;
+    ::std::vector<MacroRulesArm>    rule_arms;
+    
+    // Re-parse the patterns into a unified form
+    for(unsigned int rule_idx = 0; rule_idx < rules.size(); rule_idx ++)
+    {
+        const auto& rule = rules[rule_idx];
+        MacroRulesArm   arm( mv$(rule.m_contents) );
+        
+        enumerate_names(rule.m_pattern,  arm.m_param_names);
+        
+        auto* cur_frag = &root_frag;
+        unsigned int    frag_ofs = 0;
+        for( const auto& pat : rule.m_pattern )
+        {
+            Span    sp(pat.tok.get_pos());
+            
+            if( frag_ofs == cur_frag->m_pats_ents.size() ) {
+                if( cur_frag->m_pattern_end == ~0u && cur_frag->m_next_frags.size() == 0 ) {
+                    cur_frag->m_pats_ents.push_back( pat );
+                    frag_ofs += 1;
+                }
+                else {
+                    // Check if any of the other paths match
+                    bool found = false;
+                    for( auto& next_frag : cur_frag->m_next_frags ) {
+                        assert( next_frag.m_pats_ents.size() > 0 );
+                        if( patterns_are_same( Span(pat.tok.get_pos()), next_frag.m_pats_ents[0], pat ) ) {
+                            found = true;
+                            cur_frag = &next_frag;
+                            break;
+                        }
+                    }
+                    // If not, create a new frag
+                    if( ! found ) {
+                        cur_frag->m_next_frags.push_back( MacroRulesPatFrag() );
+                        cur_frag = &cur_frag->m_next_frags.back();
+                        cur_frag->m_pats_ents.push_back( pat );
+                    }
+                    frag_ofs = 1;
+                }
+            }
+            else if( ! patterns_are_same(sp, cur_frag->m_pats_ents[frag_ofs], pat) ) {
+                // Difference, split the block.
+                auto new_frag = split_fragment_at(*cur_frag, frag_ofs);
+                assert( cur_frag->m_next_frags.size() == 0 );
+                cur_frag->m_next_frags.push_back( mv$(new_frag) );
+                
+                // - Update cur_frag to a newly pushed fragment, and push this pattern to it
+                cur_frag->m_next_frags.push_back( MacroRulesPatFrag() );
+                cur_frag = &cur_frag->m_next_frags.back();
+                cur_frag->m_pats_ents.push_back( pat );
+                frag_ofs = 1;
+            }
+            else {
+                // Matches - Keep going
+                frag_ofs += 1;
+            }
+        }
+        
+        // If this pattern ended before the current fragment ended
+        if( frag_ofs < cur_frag->m_pats_ents.size() ) {
+            // Split the current fragment
+            auto new_frag = split_fragment_at(*cur_frag, frag_ofs);
+            assert( cur_frag->m_next_frags.size() == 0 );
+            cur_frag->m_next_frags.push_back( mv$(new_frag) );
+            // Keep cur_frag the same
+        }
+        cur_frag->m_pattern_end = rule_idx;
+        
+        rule_arms.push_back( mv$(arm) );
+    }
+    
+    // TODO: use `root_frag` above for the actual evaluation
+    
+    auto rv = new MacroRules();
+    rv->m_pattern = mv$(root_frag);
+    rv->m_rules = mv$(rule_arms);
+    
+    return MacroRulesPtr(rv);
+}
diff --git a/src/macro_rules/pattern_checks.hpp b/src/macro_rules/pattern_checks.hpp
new file mode 100644
index 00000000..820a9ef4
--- /dev/null
+++ b/src/macro_rules/pattern_checks.hpp
@@ -0,0 +1,10 @@
+/*
+ */
+#pragma once
+
+extern bool is_token_path(eTokenType tt);
+extern bool is_token_pat(eTokenType tt);
+extern bool is_token_type(eTokenType tt);
+extern bool is_token_expr(eTokenType tt);
+extern bool is_token_stmt(eTokenType tt);
+