fish-shell/src/parser.h

/** \file parser.h
  The fish parser.
*/

#ifndef FISH_PARSER_H
#define FISH_PARSER_H

#include <stddef.h>                     // for size_t
#include <list>                         // for _List_const_iterator, list, etc

#include "common.h"
#include "proc.h"
#include "event.h"
#include "parse_tree.h"
#include "io.h"
#include "parse_constants.h"
#include "expand.h"

#include <vector>

/**
   event_blockage_t represents a block on events of the specified type
*/
struct event_blockage_t
{
    /**
       The types of events to block. This is interpreted as a bitset
       whete the value is 1 for every bit corresponding to a blocked
       event type. For example, if EVENT_VARIABLE type events should
       be blocked, (type & 1<<EVENT_BLOCKED) should be set.

       Note that EVENT_ANY can be used to specify any event.
    */
    unsigned int typemask;
};

typedef std::list<event_blockage_t> event_blockage_list_t;

inline bool event_block_list_blocks_type(const event_blockage_list_t &ebls, int type)
{
    for (event_blockage_list_t::const_iterator iter = ebls.begin(); iter != ebls.end(); ++iter)
    {
        if (iter->typemask & (1<<EVENT_ANY))
            return true;
        if (iter->typemask & (1<<type))
            return true;
    }
    return false;
}


/**
  Types of blocks
*/
enum block_type_t
{
    WHILE, /**< While loop block */
    FOR,  /**< For loop block */
    IF, /**< If block */
    FUNCTION_DEF, /**< Function definition block */
    FUNCTION_CALL, /**< Function invocation block */
    FUNCTION_CALL_NO_SHADOW, /**< Function invocation block with no variable shadowing */
    SWITCH, /**< Switch block */
    FAKE, /**< Fake block */
    SUBST, /**< Command substitution scope */
    TOP, /**< Outermost block */
    BEGIN, /**< Unconditional block */
    SOURCE, /**< Block created by the . (source) builtin */
    EVENT, /**< Block created on event notifier invocation */
    BREAKPOINT, /**< Breakpoint block */
};

/** Possible states for a loop */
enum loop_status_t
{
    LOOP_NORMAL, /**< Current loop block executed as normal */
    LOOP_BREAK, /**< Current loop block should be removed */
    LOOP_CONTINUE, /**< Current loop block should be skipped */
};

/**
   block_t represents a block of commands.
*/
struct block_t
{
protected:
    /** Protected constructor. Use one of the subclasses below. */
    explicit block_t(block_type_t t);

private:
    const block_type_t block_type; /**< Type of block. */

public:
    block_type_t type() const
    {
        return this->block_type;
    }

    /** Description of the block, for debugging */
    wcstring description() const;

    bool skip; /**< Whether execution of the commands in this block should be skipped */
    int tok_pos; /**< The start index of the block */

    node_offset_t node_offset; /* Offset of the node */

    /** Status for the current loop block. Can be any of the values from the loop_status enum. */
    enum loop_status_t loop_status;

    /** The job that is currently evaluated in the specified block. */
    job_t *job;

    /** Name of file that created this block. This string is intern'd. */
    const wchar_t *src_filename;

    /** Line number where this block was created */
    int src_lineno;

    /** Whether we should pop the environment variable stack when we're popped off of the block stack */
    bool wants_pop_env;

    /** List of event blocks. */
    event_blockage_list_t event_blocks;

    /** Destructor */
    virtual ~block_t();
};

struct if_block_t : public block_t
{
    if_block_t();
};

struct event_block_t : public block_t
{
    event_t const event;
    explicit event_block_t(const event_t &evt);
};

struct function_block_t : public block_t
{
    const process_t *process;
    wcstring name;
    function_block_t(const process_t *p, const wcstring &n, bool shadows);
};

struct source_block_t : public block_t
{
    const wchar_t * const source_file;
    explicit source_block_t(const wchar_t *src);
};

struct for_block_t : public block_t
{
    for_block_t();
};

struct while_block_t : public block_t
{
    while_block_t();
};

struct switch_block_t : public block_t
{
    switch_block_t();
};

struct fake_block_t : public block_t
{
    fake_block_t();
};

struct scope_block_t : public block_t
{
    explicit scope_block_t(block_type_t type); //must be BEGIN, TOP or SUBST
};

struct breakpoint_block_t : public block_t
{
    breakpoint_block_t();
};

/**
   Errors that can be generated by the parser
*/
enum parser_error
{
    /**
       No error
    */
    NO_ERR=0,
    /**
       An error in the syntax
    */
    SYNTAX_ERROR,
    /**
       Error occured while evaluating commands
    */
    EVAL_ERROR,
    /**
       Error while evaluating cmdsubst
    */
    CMDSUBST_ERROR,
};

struct profile_item_t
{
    /** Time spent executing the specified command, including parse time for nested blocks. */
    int exec;

    /** Time spent parsing the specified command, including execution time for command substitutions. */
    int parse;

    /** The block level of the specified command. nested blocks and command substitutions both increase the block level. */
    size_t level;

    /** If the execution of this command was skipped. */
    bool skipped;

    /** The command string. */
    wcstring cmd;
};

class parse_execution_context_t;
class completion_t;

class parser_t
{
    friend class parse_execution_context_t;
private:
    /** Indication that we should skip all blocks */
    bool cancellation_requested;

    /** Indicates that we are within the process of initializing fish */
    bool is_within_fish_initialization;

    /** Stack of execution contexts. We own these pointers and must delete them */
    std::vector<parse_execution_context_t *> execution_contexts;

    /** List of called functions, used to help prevent infinite recursion */
    wcstring_list_t forbidden_function;

    /** The jobs associated with this parser */
    job_list_t my_job_list;

    /** The list of blocks, allocated with new. It's our responsibility to delete these */
    std::vector<block_t *> block_stack;

    /** Gets a description of the block stack, for debugging */
    wcstring block_stack_description() const;

    /** List of profile items, allocated with new */
    std::vector<profile_item_t *> profile_items;

    /* No copying allowed */
    parser_t(const parser_t&);
    parser_t& operator=(const parser_t&);

    /** Adds a job to the beginning of the job list. */
    void job_add(job_t *job);

    /**
       Returns the name of the currently evaluated function if we are
       currently evaluating a function, null otherwise. This is tested by
       moving down the block-scope-stack, checking every block if it is of
       type FUNCTION_CALL.
    */
    const wchar_t *is_function() const;

    /* Helper for stack_trace() */
    void stack_trace_internal(size_t block_idx, wcstring *out) const;

public:

    /** Get the "principal" parser, whatever that is */
    static parser_t &principal_parser();

    /** Indicates that execution of all blocks in the principal parser should stop.
        This is called from signal handlers!
    */
    static void skip_all_blocks();

    /** Create a parser */
    parser_t();

    /** Global event blocks */
    event_blockage_list_t global_event_blocks;

    /**
      Evaluate the expressions contained in cmd.

      \param cmd the string to evaluate
      \param io io redirections to perform on all started jobs
      \param block_type The type of block to push on the block stack

      \return 0 on success, 1 otherwise
    */
    int eval(const wcstring &cmd, const io_chain_t &io, enum block_type_t block_type);
    
    /**
       Evaluate the expressions contained in cmd, which has been parsed into the given parse tree. This takes ownership of the tree.
     */
    int eval_acquiring_tree(const wcstring &cmd, const io_chain_t &io, enum block_type_t block_type, moved_ref<parse_node_tree_t> t);

    /** Evaluates a block node at the given node offset in the topmost execution context */
    int eval_block_node(node_offset_t node_idx, const io_chain_t &io, enum block_type_t block_type);

    /**
      Evaluate line as a list of parameters, i.e. tokenize it and perform parameter expansion and cmdsubst execution on the tokens.
      The output is inserted into output.
      Errors are ignored.

      \param arg_src String to evaluate as an argument list
      \param flags Some expand flags to use
      \param output List to insert output into
    */
    static void expand_argument_list(const wcstring &arg_src, expand_flags_t flags, std::vector<completion_t> *output);

    /**
       Returns a string describing the current parser pisition in the format 'FILENAME (line LINE_NUMBER): LINE'.
       Example:

       init.fish (line 127): ls|grep pancake
    */
    wcstring current_line();

    /** Returns the current line number */
    int get_lineno() const;

    /** Returns the block at the given index. 0 corresponds to the innermost block. Returns NULL when idx is at or equal to the number of blocks. */
    const block_t *block_at_index(size_t idx) const;
    block_t *block_at_index(size_t idx);

    /** Returns the current (innermost) block */
    const block_t *current_block() const;
    block_t *current_block();

    /** Count of blocks */
    size_t block_count() const
    {
        return block_stack.size();
    }

    /** Get the list of jobs */
    job_list_t &job_list()
    {
        return my_job_list;
    }

    /* Hackish. In order to correctly report the origin of code with no associated file, we need to know whether it's run during initialization or not. */
    void set_is_within_fish_initialization(bool flag);

    /** Pushes the block. pop_block will call delete on it. */
    void push_block(block_t *newv);

    /** Remove the outermost block namespace */
    void pop_block();

    /** Remove the outermost block, asserting it's the given one */
    void pop_block(const block_t *b);

    /** Return a description of the given blocktype */
    const wchar_t *get_block_desc(int block) const;

    /** Removes a job */
    bool job_remove(job_t *job);

    /** Promotes a job to the front of the list */
    void job_promote(job_t *job);

    /** Return the job with the specified job id. If id is 0 or less, return the last job used. */
    job_t *job_get(int job_id);

    /** Returns the job with the given pid */
    job_t *job_get_from_pid(int pid);

    /* Returns a new profile item if profiling is active. The caller should fill it in. The parser_t will clean it up. */
    profile_item_t *create_profile_item();

    /**
       Test if the specified string can be parsed, or if more bytes need
       to be read first. The result will have the PARSER_TEST_ERROR bit
       set if there is a syntax error in the code, and the
       PARSER_TEST_INCOMPLETE bit set if the code contains unclosed
       blocks.

       \param buff the text buffer to test
       \param block_level if non-null, the block nesting level will be filled out into this array
       \param out if non-null, any errors in the command will be filled out into this buffer
       \param prefix the prefix string to prepend to each error message written to the \c out buffer
    */
    void get_backtrace(const wcstring &src, const parse_error_list_t &errors, wcstring *output) const;

    /**
       Detect errors in the specified string when parsed as an argument list. Returns true if an error occurred.
    */
    bool detect_errors_in_argument_list(const wcstring &arg_list_src, wcstring *out_err, const wchar_t *prefix);

    /**
       Tell the parser that the specified function may not be run if not
       inside of a conditional block. This is to remove some possibilities
       of infinite recursion.
    */
    void forbid_function(const wcstring &function);

    /**
       Undo last call to parser_forbid_function().
    */
    void allow_function();

    /**
       Output profiling data to the given filename
    */
    void emit_profiling(const char *path) const;

    /**
       Returns the file currently evaluated by the parser. This can be
       different than reader_current_filename, e.g. if we are evaulating a
       function defined in a different file than the one curently read.
    */
    const wchar_t *current_filename() const;

    /**
       Return a string representing the current stack trace
    */
    wcstring stack_trace() const;
};

#endif