diff --git a/builtin.cpp b/builtin.cpp
index 9796d356f..12b331b82 100644
--- a/builtin.cpp
+++ b/builtin.cpp
@@ -64,6 +64,8 @@
 #include "expand.h"
 #include "path.h"
 #include "history.h"
+#include "parse_tree.h"
+#include "parse_exec.h"
 
 /**
    The default prompt for the read command
@@ -3938,6 +3940,30 @@ static int builtin_history(parser_t &parser, wchar_t **argv)
     return STATUS_BUILTIN_ERROR;
 }
 
+int builtin_parse(parser_t &parser, wchar_t **argv)
+{
+    std::vector<char> txt;
+    for (;;)
+    {
+        char buff[256];
+        ssize_t amt = read_loop(builtin_stdin, buff, sizeof buff);
+        if (amt <= 0) break;
+        txt.insert(txt.end(), buff, buff + amt);
+    }
+    if (! txt.empty())
+    {
+        const wcstring src = str2wcstring(&txt.at(0), txt.size());
+        parse_node_tree_t parse_tree;
+        parse_t parser;
+        parser.parse(src, &parse_tree);
+        parse_execution_context_t ctx(parse_tree, src);
+        stdout_buffer.append(L"Simulating execution:");
+        wcstring simulation = ctx.simulate();
+        stdout_buffer.append(simulation);
+        stdout_buffer.push_back(L'\n');
+    }
+    return STATUS_BUILTIN_OK;
+}
 
 /*
   END OF BUILTIN COMMANDS
@@ -3985,6 +4011,7 @@ static const builtin_data_t builtin_datas[]=
     { 		L"jobs",  &builtin_jobs, N_(L"Print currently running jobs")   },
     { 		L"not",  &builtin_generic, N_(L"Negate exit status of job")  },
     { 		L"or",  &builtin_generic, N_(L"Execute command if previous command failed")  },
+    { 		L"parse",  &builtin_parse, N_(L"Try out the new parser")  },
     { 		L"printf",  &builtin_printf, N_(L"Prints formatted text")  },
     { 		L"pwd",  &builtin_pwd, N_(L"Print the working directory")  },
     { 		L"random",  &builtin_random, N_(L"Generate random number")  },
@@ -4144,4 +4171,3 @@ void builtin_pop_io(parser_t &parser)
         builtin_stdin = 0;
     }
 }
-
diff --git a/fish_tests.cpp b/fish_tests.cpp
index 35c1e3277..20d79288b 100644
--- a/fish_tests.cpp
+++ b/fish_tests.cpp
@@ -1722,8 +1722,16 @@ void history_tests_t::test_history_speed(void)
 static void test_new_parser(void)
 {
     say(L"Testing new parser!");
+    const wcstring src = L"echo hello world";
+    parse_node_tree_t parse_tree;
     parse_t parser;
-    parser.parse(L"echo hello");
+    parser.parse(src, &parse_tree);
+    parse_execution_context_t ctx(parse_tree, src);
+    say(L"Simulating execution:");
+    wcstring simulation = ctx.simulate();
+    printf("%ls\n", simulation.c_str());
+    
+    
 }
 
 /**
diff --git a/parse_exec.cpp b/parse_exec.cpp
index 30503857e..04601e5ba 100644
--- a/parse_exec.cpp
+++ b/parse_exec.cpp
@@ -1,34 +1,41 @@
 #include "parse_exec.h"
 #include <stack>
 
+typedef uint16_t sanity_id_t;
+static sanity_id_t next_sanity_id()
+{
+    static sanity_id_t last_sanity_id;
+    return ++last_sanity_id;
+}
 
 struct exec_node_t
 {
     node_offset_t parse_node_idx;
+    sanity_id_t command_sanity_id;
     
     exec_node_t(size_t pni) : parse_node_idx(pni)
     {
     }
     
-    virtual ~exec_node_t();
 };
 
-exec_node_t::~exec_node_t()
+struct exec_argument_t
 {
-}
+    node_offset_t parse_node_idx;
+    sanity_id_t command_sanity_id;
+};
 
-struct exec_redirection_t : public exec_node_t
+struct exec_redirection_t
 {
 
 };
 
-struct exec_argument_t : public exec_node_t
+struct exec_basic_statement_t
 {
+    // Node containing the command
+    node_offset_t command_idx;
     
-};
-
-struct exec_statement_t
-{
+    // Decoration
     enum
     {
         decoration_plain,
@@ -38,68 +45,260 @@ struct exec_statement_t
     
     std::vector<exec_argument_t> arguments;
     std::vector<exec_redirection_t> redirections;
+    uint16_t sanity_id;
+    
+    exec_basic_statement_t() : command_idx(0), decoration(decoration_plain)
+    {
+        sanity_id = next_sanity_id();
+    }
+    
+    void set_decoration(uint32_t k)
+    {
+        PARSE_ASSERT(k == parse_keyword_none || k == parse_keyword_command || k == parse_keyword_builtin);
+        switch (k)
+        {
+            case parse_keyword_none:
+                decoration = decoration_plain;
+                break;
+            case parse_keyword_command:
+                decoration = decoration_command;
+                break;
+            case parse_keyword_builtin:
+                decoration = decoration_builtin;
+                break;
+            default:
+                PARSER_DIE();
+                break;
+        }
+                
+    }
 };
 
 class parse_exec_t
 {
     parse_node_tree_t parse_tree;
     wcstring src;
+    
+    bool simulating;
+    wcstring_list_t simulation_result;
+    
+    /* The stack of nodes as we execute them */
     std::vector<exec_node_t> exec_nodes;
     
-    parse_exec_t(const parse_node_tree_t &tree, const wcstring &s) : parse_tree(tree), src(s)
+    /* The stack of commands being built */
+    std::vector<exec_basic_statement_t> assembling_statements;
+    
+    void get_node_string(node_offset_t idx, wcstring *output) const
     {
+        const parse_node_t &node = parse_tree.at(idx);
+        PARSE_ASSERT(node.source_start <= src.size());
+        PARSE_ASSERT(node.source_start + node.source_length <= src.size());
+        output->assign(src, node.source_start, node.source_length);
+    }
+        
+    void pop_push(node_offset_t child_idx, node_offset_t child_count = 1)
+    {
+        PARSE_ASSERT(! exec_nodes.empty());
+        if (child_count == 0)
+        {
+            // No children, just remove the top node
+            exec_nodes.pop_back();
+        }
+        else
+        {
+            // Figure out the offset of the children
+            exec_node_t &top = exec_nodes.back();
+            const parse_node_t &parse_node = parse_tree.at(top.parse_node_idx);
+            PARSE_ASSERT(child_idx < parse_node.child_count);
+            node_offset_t child_node_idx = parse_node.child_start + child_idx;
+            
+            // Remove the top node
+            exec_nodes.pop_back();
+            
+            // Append the given children, backwards
+            sanity_id_t command_sanity_id = assembling_statements.empty() ? 0 : assembling_statements.back().sanity_id;
+            node_offset_t cursor = child_count;
+            while (cursor--)
+            {
+                exec_nodes.push_back(child_node_idx + cursor);
+                exec_nodes.back().command_sanity_id = command_sanity_id;
+            }
+        }
     }
     
-    void pop_push(uint32_t child_idx)
+    void pop()
+    {
+        PARSE_ASSERT(! exec_nodes.empty());
+        exec_nodes.pop_back();
+    }
+    
+    void pop_push_all()
     {
         exec_node_t &top = exec_nodes.back();
         const parse_node_t &parse_node = parse_tree.at(top.parse_node_idx);
-        PARSE_ASSERT(child_idx < parse_node.child_count);
-        node_offset_t child_node_idx = parse_node.child_start + child_idx;
-        exec_nodes.pop_back();
-        exec_nodes.push_back(child_node_idx);
+        pop_push(0, parse_node.child_count);
+    }
+    
+    void assemble_command(node_offset_t idx)
+    {
+        // Set the command for our top basic statement
+        PARSE_ASSERT(! assembling_statements.empty());
+        assembling_statements.back().command_idx = idx;
+    }
+    
+    void assemble_argument_or_redirection(node_offset_t idx)
+    {
+        const parse_node_t &node = parse_tree.at(idx);
+        PARSE_ASSERT(! assembling_statements.empty());
+        exec_basic_statement_t &statement = assembling_statements.back();
+        switch (node.type)
+        {
+            case parse_token_type_string:
+                // Argument
+                {
+                    exec_argument_t arg = exec_argument_t();
+                    arg.parse_node_idx = idx;
+                    arg.command_sanity_id = statement.sanity_id;
+                    statement.arguments.push_back(arg);
+                }
+                break;
+                
+            case parse_token_type_redirection:
+                // Redirection
+                break;
+                
+            default:
+                PARSER_DIE();
+                break;
+        }
         
     }
     
-    void simulate(void);
+    void assembly_complete()
+    {
+        // Finished building a command
+        PARSE_ASSERT(! assembling_statements.empty());
+        const exec_basic_statement_t &statement = assembling_statements.back();
+        
+        if (simulating)
+        {
+            simulate_statement(statement);
+        }
+        assembling_statements.pop_back();
+    }
+    
+    void simulate_statement(const exec_basic_statement_t &statement)
+    {
+        PARSE_ASSERT(simulating);
+        wcstring line;
+        switch (statement.decoration)
+        {
+            case exec_basic_statement_t::decoration_builtin:
+                line.append(L"<builtin> ");
+                break;
+            
+            case exec_basic_statement_t::decoration_command:
+                line.append(L"<command> ");
+                break;
+                
+            default:
+            break;
+        }
+        
+        wcstring tmp;
+        get_node_string(statement.command_idx, &tmp);
+        line.append(L"cmd:");
+        line.append(tmp);
+        for (size_t i=0; i < statement.arguments.size(); i++)
+        {
+            const exec_argument_t &arg = statement.arguments.at(i);
+            get_node_string(arg.parse_node_idx, &tmp);
+            line.append(L" ");
+            line.append(L"arg:");            
+            line.append(tmp);
+        }
+        simulation_result.push_back(line);
+    }
+    
     void enter_parse_node(size_t idx);
     void run_top_node(void);
+    exec_basic_statement_t *create_basic_statement(void);
+    
+    public:
+    parse_exec_t(const parse_node_tree_t &tree, const wcstring &s) : parse_tree(tree), src(s), simulating(false)
+    {
+    }
+    wcstring simulate(void);
 };
 
+exec_basic_statement_t *parse_exec_t::create_basic_statement()
+{
+    assembling_statements.push_back(exec_basic_statement_t());
+    return &assembling_statements.back();
+}
+
 void parse_exec_t::run_top_node()
 {
     PARSE_ASSERT(! exec_nodes.empty());
     exec_node_t &top = exec_nodes.back();
     const parse_node_t &parse_node = parse_tree.at(top.parse_node_idx);
+    bool log = false;
+    
+    if (log)
+    {
+        wcstring tmp;
+        tmp.append(exec_nodes.size(), L' ');
+        tmp.append(parse_node.describe());
+        printf("%ls\n", tmp.c_str());
+    }
     
     switch (parse_node.type)
     {
         case symbol_statement_list:
             PARSE_ASSERT(parse_node.child_count == 0 || parse_node.child_count == 2);
-            if (parse_node.child_count == 0)
-            {
-                // Statement list done
-                exec_nodes.pop_back();
-            }
-            else
-            {
-                // First child is a statement, next is the rest of the list
-                node_offset_t head = parse_node.child_start;
-                node_offset_t tail = parse_node.child_start + 1;
-                exec_nodes.pop_back();
-                exec_nodes.push_back(tail);
-                exec_nodes.push_back(head);
-            }
+            pop_push_all();
             break;
             
         case symbol_statement:
             PARSE_ASSERT(parse_node.child_count == 1);
-            pop_push(0);
+            pop_push_all();
             break;
             
-        case decorated_statement:
+        case symbol_decorated_statement:
+        {
             PARSE_ASSERT(parse_node.child_count == 1 || parse_node.child_count == 2 );
-            pop_push(0);
+            exec_basic_statement_t *cmd = create_basic_statement();
+            cmd->set_decoration(parse_node.tag);
+            
+            // Push the last node (skip any decoration)
+            pop_push(parse_node.child_count - 1, 1);
+            break;
+        }
+            
+        case symbol_plain_statement:
+            PARSE_ASSERT(parse_node.child_count == 3);
+            // Extract the command
+            PARSE_ASSERT(! assembling_statements.empty());
+            assemble_command(parse_node.child_start + 0);
+            // Jump to statement list, then terminator
+            pop_push(1, 2);
+            break;
+            
+        case symbol_arguments_or_redirections_list:
+            PARSE_ASSERT(parse_node.child_count == 0 || parse_node.child_count == 2);
+            pop_push_all();
+            break;
+        
+        case symbol_argument_or_redirection:
+            PARSE_ASSERT(parse_node.child_count == 1);
+            assemble_argument_or_redirection(parse_node.child_start + 0);
+            pop();
+            break;
+            
+        case parse_token_type_end:
+            PARSE_ASSERT(parse_node.child_count == 0);
+            assembly_complete();
+            pop();
             break;
             
         default:
@@ -118,23 +317,27 @@ void parse_exec_t::enter_parse_node(size_t idx)
 }
 
 wcstring parse_exec_t::simulate(void)
-{
-    PARSE_ASSERT(exec_nodes.empty());
-    assemble_statement_list(0);
-    enter_parse_node(0);
-    run_node();
-}
-
-wcstring parse_execution_context_t::simulate()
 {
     if (parse_tree.empty())
         return L"(empty!)";
     
-    PARSE_ASSERT(node_idx < nodes.size());
-    PARSE_ASSERT(nodes.at(node_idx).type == symbol_statement_list);
+    PARSE_ASSERT(exec_nodes.empty());
+    simulating = true;
+    
+    enter_parse_node(0);
+    while (! exec_nodes.empty())
+    {
+        run_top_node();
+    }
     
     wcstring result;
+    for (size_t i=0; i < simulation_result.size(); i++)
+    {
+        result.append(simulation_result.at(i));
+        result.append(L"\n");
+    }
     
+    return result;
 }
 
 parse_execution_context_t::parse_execution_context_t(const parse_node_tree_t &n, const wcstring &s)
diff --git a/parse_tree.cpp b/parse_tree.cpp
index 8c38ff0cd..a58b0ff80 100644
--- a/parse_tree.cpp
+++ b/parse_tree.cpp
@@ -634,7 +634,7 @@ static parse_keyword_t keyword_for_token(token_type tok, const wchar_t *tok_txt)
     return result;
 }
 
-void parse_t::parse(const wcstring &str)
+void parse_t::parse(const wcstring &str, parse_node_tree_t *output)
 {
     tokenizer_t tok = tokenizer_t(str.c_str(), 0);
     for (; tok_has_next(&tok); tok_next(&tok))
@@ -658,5 +658,11 @@ void parse_t::parse(const wcstring &str)
     }
     wcstring result = dump_tree(this->parser->nodes, str);
     fprintf(stderr, "Tree (%ld nodes):\n%ls", this->parser->nodes.size(), result.c_str());
-    fprintf(stderr, "node size %ld\n", sizeof(parse_node_t));
+    fprintf(stderr, "%lu nodes, node size %lu, %lu bytes\n", this->parser->nodes.size(), sizeof(parse_node_t), this->parser->nodes.size() * sizeof(parse_node_t));
+    
+    if (output != NULL)
+    {
+        output->swap(this->parser->nodes);
+        this->parser->nodes.clear();
+    }
 }
diff --git a/parse_tree.h b/parse_tree.h
index 892c36cdd..0b63efa82 100644
--- a/parse_tree.h
+++ b/parse_tree.h
@@ -17,22 +17,21 @@
 #define PARSE_ASSERT(a) assert(a)
 #define PARSER_DIE() assert(0)
 
+class parse_node_t;
+typedef std::vector<parse_node_t> parse_node_tree_t;
+typedef size_t node_offset_t;
+
 
 class parse_ll_t;
-class parse_sr_t;
 class parse_t
 {
     parse_ll_t * const parser;
     
     public:
     parse_t();
-    void parse(const wcstring &str);
+    void parse(const wcstring &str, parse_node_tree_t *output);
 };
 
-class parse_node_t;
-typedef std::vector<parse_node_t> parse_node_tree_t;
-typedef size_t node_offset_t;
-
 
 enum parse_token_type_t
 {