src/vim9.h

/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * vim9.h: types and globals used for Vim9 script.
 */

#ifdef VMS
# include <float.h>
#endif

typedef enum {
    ISN_EXEC,	    // execute Ex command line isn_arg.string
    ISN_EXECCONCAT, // execute Ex command from isn_arg.number items on stack
    ISN_EXEC_SPLIT, // execute Ex command from isn_arg.string split at NL
    ISN_EXECRANGE,  // execute EX command that is only a range
    ISN_LEGACY_EVAL, // evaluate expression isn_arg.string with legacy syntax.
    ISN_ECHO,	    // :echo with isn_arg.echo.echo_count items on top of stack
    ISN_EXECUTE,    // :execute with isn_arg.number items on top of stack
    ISN_ECHOMSG,    // :echomsg with isn_arg.number items on top of stack
    ISN_ECHOCONSOLE, // :echoconsole with isn_arg.number items on top of stack
    ISN_ECHOWINDOW, // :echowindow with isn_arg.number items on top of stack
    ISN_ECHOERR,    // :echoerr with isn_arg.number items on top of stack
    ISN_RANGE,	    // compute range from isn_arg.string, push to stack
    ISN_SUBSTITUTE, // :s command with expression

    ISN_SOURCE,	    // source autoload script, isn_arg.number is the script ID
    ISN_INSTR,	    // instructions compiled from expression

    // get and set variables
    ISN_LOAD,	    // push local variable isn_arg.number
    ISN_LOADV,	    // push v: variable isn_arg.number
    ISN_LOADG,	    // push g: variable isn_arg.string
    ISN_LOADAUTO,   // push g: autoload variable isn_arg.string
    ISN_LOADB,	    // push b: variable isn_arg.string
    ISN_LOADW,	    // push w: variable isn_arg.string
    ISN_LOADT,	    // push t: variable isn_arg.string
    ISN_LOADGDICT,  // push g: dict
    ISN_LOADBDICT,  // push b: dict
    ISN_LOADWDICT,  // push w: dict
    ISN_LOADTDICT,  // push t: dict
    ISN_LOADS,	    // push s: variable isn_arg.loadstore
    ISN_LOADEXPORT, // push exported variable isn_arg.loadstore
    ISN_LOADOUTER,  // push variable from outer scope isn_arg.outer
    ISN_LOADSCRIPT, // push script-local variable isn_arg.script.
    ISN_LOADOPT,    // push option isn_arg.string
    ISN_LOADENV,    // push environment variable isn_arg.string
    ISN_LOADREG,    // push register isn_arg.number

    ISN_STORE,	    // pop into local variable isn_arg.number
    ISN_STOREV,	    // pop into v: variable isn_arg.number
    ISN_STOREG,	    // pop into global variable isn_arg.string
    ISN_STOREAUTO,  // pop into global autoload variable isn_arg.string
    ISN_STOREB,	    // pop into buffer-local variable isn_arg.string
    ISN_STOREW,	    // pop into window-local variable isn_arg.string
    ISN_STORET,	    // pop into tab-local variable isn_arg.string
    ISN_STORES,	    // pop into script variable isn_arg.loadstore
    ISN_STOREEXPORT, // pop into exported script variable isn_arg.loadstore
    ISN_STOREOUTER,  // pop variable into outer scope isn_arg.outer
    ISN_STORESCRIPT, // pop into script variable isn_arg.script
    ISN_STOREOPT,    // pop into option isn_arg.storeopt
    ISN_STOREFUNCOPT, // pop into option isn_arg.storeopt
    ISN_STOREENV,    // pop into environment variable isn_arg.string
    ISN_STOREREG,    // pop into register isn_arg.number
    // ISN_STOREOTHER, // pop into other script variable isn_arg.other.

    ISN_STORENR,    // store number into local variable isn_arg.storenr.stnr_idx
    ISN_STOREINDEX,	// store into list or dictionary, type isn_arg.vartype,
			// value/index/variable on stack
    ISN_STORERANGE,	// store into blob,
			// value/index 1/index 2/variable on stack

    ISN_UNLET,		// unlet variable isn_arg.unlet.ul_name
    ISN_UNLETENV,	// unlet environment variable isn_arg.unlet.ul_name
    ISN_UNLETINDEX,	// unlet item of list or dict
    ISN_UNLETRANGE,	// unlet items of list

    ISN_LOCKUNLOCK,	// :lock and :unlock for local variable member
    ISN_LOCKCONST,	// lock constant value

    // constants
    ISN_PUSHNR,		// push number isn_arg.number
    ISN_PUSHBOOL,	// push bool value isn_arg.number
    ISN_PUSHSPEC,	// push special value isn_arg.number
    ISN_PUSHF,		// push float isn_arg.fnumber
    ISN_PUSHS,		// push string isn_arg.string
    ISN_PUSHBLOB,	// push blob isn_arg.blob
    ISN_PUSHFUNC,	// push func isn_arg.string
    ISN_PUSHCHANNEL,	// push NULL channel
    ISN_PUSHJOB,	// push NULL job
    ISN_NEWLIST,	// push list from stack items, size is isn_arg.number
			// -1 for null_list
    ISN_NEWDICT,	// push dict from stack items, size is isn_arg.number
			// -1 for null_dict
    ISN_NEWPARTIAL,	// push NULL partial

    ISN_AUTOLOAD,	// get item from autoload import, function or variable

    // function call
    ISN_BCALL,	    // call builtin function isn_arg.bfunc
    ISN_DCALL,	    // call def function isn_arg.dfunc
    ISN_UCALL,	    // call user function or funcref/partial isn_arg.ufunc
    ISN_PCALL,	    // call partial, use isn_arg.pfunc
    ISN_PCALL_END,  // cleanup after ISN_PCALL with cpf_top set
    ISN_RETURN,	    // return, result is on top of stack
    ISN_RETURN_VOID, // Push void, then return
    ISN_FUNCREF,    // push a function ref to dfunc isn_arg.funcref
    ISN_NEWFUNC,    // create a global function from a lambda function
    ISN_DEF,	    // list functions

    // expression operations
    ISN_JUMP,	    // jump if condition is matched isn_arg.jump
    ISN_JUMP_IF_ARG_SET, // jump if argument is already set, uses
			 // isn_arg.jumparg

    // loop
    ISN_FOR,	    // get next item from a list, uses isn_arg.forloop

    ISN_TRY,	    // add entry to ec_trystack, uses isn_arg.tryref
    ISN_THROW,	    // pop value of stack, store in v:exception
    ISN_PUSHEXC,    // push v:exception
    ISN_CATCH,	    // drop v:exception
    ISN_FINALLY,    // start of :finally block
    ISN_ENDTRY,	    // take entry off from ec_trystack
    ISN_TRYCONT,    // handle :continue or :break inside a :try statement

    // more expression operations
    ISN_ADDLIST,    // add two lists
    ISN_ADDBLOB,    // add two blobs

    // operation with two arguments; isn_arg.op.op_type is exprtype_T
    ISN_OPNR,
    ISN_OPFLOAT,
    ISN_OPANY,

    // comparative operations; isn_arg.op.op_type is exprtype_T, op_ic used
    ISN_COMPAREBOOL,
    ISN_COMPARESPECIAL,
    ISN_COMPARENULL,
    ISN_COMPARENR,
    ISN_COMPAREFLOAT,
    ISN_COMPARESTRING,
    ISN_COMPAREBLOB,
    ISN_COMPARELIST,
    ISN_COMPAREDICT,
    ISN_COMPAREFUNC,
    ISN_COMPAREANY,

    // expression operations
    ISN_CONCAT,     // concatenate isn_arg.number strings
    ISN_STRINDEX,   // [expr] string index
    ISN_STRSLICE,   // [expr:expr] string slice
    ISN_LISTAPPEND, // append to a list, like add()
    ISN_LISTINDEX,  // [expr] list index
    ISN_LISTSLICE,  // [expr:expr] list slice
    ISN_BLOBINDEX,  // [expr] blob index
    ISN_BLOBSLICE,  // [expr:expr] blob slice
    ISN_ANYINDEX,   // [expr] runtime index
    ISN_ANYSLICE,   // [expr:expr] runtime slice
    ISN_SLICE,	    // drop isn_arg.number items from start of list
    ISN_BLOBAPPEND, // append to a blob, like add()
    ISN_GETITEM,    // push list item, isn_arg.number is the index
    ISN_MEMBER,	    // dict[member]
    ISN_STRINGMEMBER, // dict.member using isn_arg.string
    ISN_2BOOL,	    // falsy/truthy to bool, uses isn_arg.tobool
    ISN_COND2BOOL,  // convert value to bool
    ISN_2STRING,    // convert value to string at isn_arg.tostring on stack
    ISN_2STRING_ANY, // like ISN_2STRING but check type
    ISN_NEGATENR,   // apply "-" to number

    ISN_CHECKTYPE,  // check value type is isn_arg.type.ct_type
    ISN_CHECKLEN,   // check list length is isn_arg.checklen.cl_min_len
    ISN_SETTYPE,    // set dict type to isn_arg.type.ct_type

    ISN_CLEARDICT,  // clear dict saved by ISN_MEMBER/ISN_STRINGMEMBER
    ISN_USEDICT,    // use or clear dict saved by ISN_MEMBER/ISN_STRINGMEMBER

    ISN_PUT,	    // ":put", uses isn_arg.put

    ISN_CMDMOD,	    // set cmdmod
    ISN_CMDMOD_REV, // undo ISN_CMDMOD

    ISN_PROF_START, // start a line for profiling
    ISN_PROF_END,   // end a line for profiling

    ISN_DEBUG,	    // check for debug breakpoint, uses isn_arg.debug

    ISN_UNPACK,	    // unpack list into items, uses isn_arg.unpack
    ISN_SHUFFLE,    // move item on stack up or down
    ISN_DROP,	    // pop stack and discard value

    ISN_REDIRSTART, // :redir =>
    ISN_REDIREND,   // :redir END, isn_arg.number == 1 for append

    ISN_CEXPR_AUCMD, // first part of :cexpr  isn_arg.number is cmdidx
    ISN_CEXPR_CORE,  // second part of :cexpr, uses isn_arg.cexpr

    ISN_FINISH	    // end marker in list of instructions
} isntype_T;


// arguments to ISN_BCALL
typedef struct {
    int	    cbf_idx;	    // index in "global_functions"
    int	    cbf_argcount;   // number of arguments on top of stack
} cbfunc_T;

// arguments to ISN_DCALL
typedef struct {
    int	    cdf_idx;	    // index in "def_functions" for ISN_DCALL
    int	    cdf_argcount;   // number of arguments on top of stack
} cdfunc_T;

// arguments to ISN_PCALL
typedef struct {
    int	    cpf_top;	    // when TRUE partial is above the arguments
    int	    cpf_argcount;   // number of arguments on top of stack
} cpfunc_T;

// arguments to ISN_UCALL and ISN_XCALL
typedef struct {
    char_u  *cuf_name;
    int	    cuf_argcount;   // number of arguments on top of stack
} cufunc_T;

// arguments to ISN_GETITEM
typedef struct {
    varnumber_T	gi_index;
    int		gi_with_op;
} getitem_T;

typedef enum {
    JUMP_ALWAYS,
    JUMP_NEVER,
    JUMP_IF_FALSE,		// pop and jump if false
    JUMP_AND_KEEP_IF_TRUE,	// jump if top of stack is truthy, drop if not
    JUMP_IF_COND_TRUE,		// jump if top of stack is true, drop if not
    JUMP_IF_COND_FALSE,		// jump if top of stack is false, drop if not
} jumpwhen_T;

// arguments to ISN_JUMP
typedef struct {
    jumpwhen_T	jump_when;
    int		jump_where;	    // position to jump to
} jump_T;

// arguments to ISN_JUMP_IF_ARG_SET
typedef struct {
    int		jump_arg_off;	    // argument index, negative
    int		jump_where;	    // position to jump to
} jumparg_T;

// arguments to ISN_FOR
typedef struct {
    int	    for_idx;	    // loop variable index
    int	    for_end;	    // position to jump to after done
} forloop_T;

// indirect arguments to ISN_TRY
typedef struct {
    int	    try_catch;	    // position to jump to on throw
    int	    try_finally;    // :finally or :endtry position to jump to
    int	    try_endtry;	    // :endtry position to jump to
} tryref_T;

// arguments to ISN_TRY
typedef struct {
    tryref_T *try_ref;
} try_T;

// arguments to ISN_TRYCONT
typedef struct {
    int	    tct_levels;	    // number of nested try statements
    int	    tct_where;	    // position to jump to, WHILE or FOR
} trycont_T;

// arguments to ISN_ECHO
typedef struct {
    int	    echo_with_white;    // :echo instead of :echon
    int	    echo_count;		// number of expressions
} echo_T;

// arguments to ISN_OPNR, ISN_OPFLOAT, etc.
typedef struct {
    exprtype_T	op_type;
    int		op_ic;	    // TRUE with '#', FALSE with '?', else MAYBE
} opexpr_T;

// arguments to ISN_CHECKTYPE
typedef struct {
    type_T	*ct_type;
    int8_T	ct_off;		// offset in stack, -1 is bottom
    int8_T	ct_arg_idx;	// argument index or zero
    int8_T	ct_is_var;	// when TRUE checking variable instead of arg
} checktype_T;

// arguments to ISN_STORENR
typedef struct {
    int		stnr_idx;
    varnumber_T	stnr_val;
} storenr_T;

// arguments to ISN_STOREOPT and ISN_STOREFUNCOPT
typedef struct {
    char_u	*so_name;
    int		so_flags;
} storeopt_T;

// arguments to ISN_LOADS and ISN_STORES
typedef struct {
    char_u	*ls_name;	// variable name (with s: for ISN_STORES)
    int		ls_sid;		// script ID
} loadstore_T;

// arguments to ISN_LOADSCRIPT and ISN_STORESCRIPT
typedef struct {
    int		sref_sid;	// script ID
    int		sref_idx;	// index in sn_var_vals
    int		sref_seq;	// sn_script_seq when compiled
    type_T	*sref_type;	// type of the variable when compiled
} scriptref_T;

typedef struct {
    scriptref_T	*scriptref;
} script_T;

// arguments to ISN_UNLET
typedef struct {
    char_u	*ul_name;	// variable name with g:, w:, etc.
    int		ul_forceit;	// forceit flag
} unlet_T;

// arguments to ISN_FUNCREF
typedef struct {
    int		fr_dfunc_idx;	// function index for :def function
    char_u	*fr_func_name;	// function name for legacy function
} funcref_T;

// arguments to ISN_NEWFUNC
typedef struct {
    char_u	*nf_lambda;	// name of the lambda already defined
    char_u	*nf_global;	// name of the global function to be created
} newfunc_T;

// arguments to ISN_CHECKLEN
typedef struct {
    int		cl_min_len;	// minimum length
    int		cl_more_OK;	// longer is allowed
} checklen_T;

// arguments to ISN_SHUFFLE
typedef struct {
    int		shfl_item;	// item to move (relative to top of stack)
    int		shfl_up;	// places to move upwards
} shuffle_T;

// arguments to ISN_PUT
typedef struct {
    int		put_regname;	// register, can be NUL
    linenr_T	put_lnum;	// line number to put below
} put_T;

// arguments to ISN_CMDMOD
typedef struct {
    cmdmod_T	*cf_cmdmod;	// allocated
} cmod_T;

// arguments to ISN_UNPACK
typedef struct {
    int		unp_count;	// number of items to produce
    int		unp_semicolon;	// last item gets list of remainder
} unpack_T;

// arguments to ISN_LOADOUTER and ISN_STOREOUTER
typedef struct {
    int		outer_idx;	// index
    int		outer_depth;	// nesting level, stack frames to go up
} isn_outer_T;

// arguments to ISN_SUBSTITUTE
typedef struct {
    char_u	*subs_cmd;	// :s command
    isn_T	*subs_instr;	// sequence of instructions
} subs_T;

// indirect arguments to ISN_TRY
typedef struct {
    int		cer_cmdidx;
    char_u	*cer_cmdline;
    int		cer_forceit;
} cexprref_T;

// arguments to ISN_CEXPR_CORE
typedef struct {
    cexprref_T *cexpr_ref;
} cexpr_T;

// arguments to ISN_2STRING and ISN_2STRING_ANY
typedef struct {
    int		offset;
    int		tolerant;
} tostring_T;

// arguments to ISN_2BOOL
typedef struct {
    int		offset;
    int		invert;
} tobool_T;

// arguments to ISN_DEBUG
typedef struct {
    varnumber_T	dbg_var_names_len;  // current number of local variables
    int		dbg_break_lnum;	    // first line to break after
} debug_T;

/*
 * Instruction
 */
struct isn_S {
    isntype_T	isn_type;
    int		isn_lnum;
    union {
	char_u		    *string;
	varnumber_T	    number;
	blob_T		    *blob;
	vartype_T	    vartype;
#ifdef FEAT_FLOAT
	float_T		    fnumber;
#endif
	channel_T	    *channel;
	job_T		    *job;
	partial_T	    *partial;
	jump_T		    jump;
	jumparg_T	    jumparg;
	forloop_T	    forloop;
	try_T		    tryref;
	trycont_T	    trycont;
	cbfunc_T	    bfunc;
	cdfunc_T	    dfunc;
	cpfunc_T	    pfunc;
	cufunc_T	    ufunc;
	echo_T		    echo;
	opexpr_T	    op;
	checktype_T	    type;
	storenr_T	    storenr;
	storeopt_T	    storeopt;
	loadstore_T	    loadstore;
	script_T	    script;
	unlet_T		    unlet;
	funcref_T	    funcref;
	newfunc_T	    newfunc;
	checklen_T	    checklen;
	shuffle_T	    shuffle;
	put_T		    put;
	cmod_T		    cmdmod;
	unpack_T	    unpack;
	isn_outer_T	    outer;
	subs_T		    subs;
	cexpr_T		    cexpr;
	isn_T		    *instr;
	tostring_T	    tostring;
	tobool_T	    tobool;
	getitem_T	    getitem;
	debug_T		    debug;
    } isn_arg;
};

/*
 * Info about a function defined with :def.  Used in "def_functions".
 */
struct dfunc_S {
    ufunc_T	*df_ufunc;	    // struct containing most stuff
    int		df_refcount;	    // how many ufunc_T point to this dfunc_T
    int		df_idx;		    // index in def_functions
    int		df_deleted;	    // if TRUE function was deleted
    int		df_script_seq;	    // Value of sctx_T sc_seq when the function
				    // was compiled.
    char_u	*df_name;	    // name used for error messages

    garray_T	df_def_args_isn;    // default argument instructions
    garray_T	df_var_names;	    // names of local vars

    // After compiling "df_instr" and/or "df_instr_prof" is not NULL.
    isn_T	*df_instr;	    // function body to be executed
    int		df_instr_count;	    // size of "df_instr"
    int		df_instr_debug_count; // size of "df_instr_debug"
    isn_T	*df_instr_debug;      // like "df_instr" with debugging
#ifdef FEAT_PROFILE
    isn_T	*df_instr_prof;	     // like "df_instr" with profiling
    int		df_instr_prof_count; // size of "df_instr_prof"
#endif

    int		df_varcount;	    // number of local variables
    int		df_has_closure;	    // one if a closure was created
};

// Number of entries used by stack frame for a function call.
// - ec_dfunc_idx:   function index
// - ec_iidx:	     instruction index
// - ec_instr:       instruction list pointer
// - ec_outer:	     stack used for closures
// - funclocal:	     function-local data
// - ec_frame_idx:   previous frame index
#define STACK_FRAME_FUNC_OFF 0
#define STACK_FRAME_IIDX_OFF 1
#define STACK_FRAME_INSTR_OFF 2
#define STACK_FRAME_OUTER_OFF 3
#define STACK_FRAME_FUNCLOCAL_OFF 4
#define STACK_FRAME_IDX_OFF 5
#define STACK_FRAME_SIZE 6


extern garray_T def_functions;

// Used for "lnum" when a range is to be taken from the stack.
#define LNUM_VARIABLE_RANGE (-999)

// Used for "lnum" when a range is to be taken from the stack and "!" is used.
#define LNUM_VARIABLE_RANGE_ABOVE (-888)

// Keep in sync with get_compile_type()
#ifdef FEAT_PROFILE
# define INSTRUCTIONS(dfunc) \
	(debug_break_level > 0 || may_break_in_function(dfunc->df_ufunc) \
	    ? (dfunc)->df_instr_debug \
	    : ((do_profiling == PROF_YES && (dfunc->df_ufunc)->uf_profiling) \
		? (dfunc)->df_instr_prof \
		: (dfunc)->df_instr))
#else
# define INSTRUCTIONS(dfunc) \
	(debug_break_level > 0 || may_break_in_function((dfunc)->df_ufunc) \
		? (dfunc)->df_instr_debug \
		: (dfunc)->df_instr)
#endif

// Structure passed between the compile_expr* functions to keep track of
// constants that have been parsed but for which no code was produced yet.  If
// possible expressions on these constants are applied at compile time.  If
// that is not possible, the code to push the constants needs to be generated
// before other instructions.
// Using 50 should be more than enough of 5 levels of ().
#define PPSIZE 50
typedef struct {
    typval_T	pp_tv[PPSIZE];	// stack of ppconst constants
    int		pp_used;	// active entries in pp_tv[]
    int		pp_is_const;	// all generated code was constants, used for a
				// list or dict with constant members
} ppconst_T;

// values for ctx_skip
typedef enum {
    SKIP_NOT,		// condition is a constant, produce code
    SKIP_YES,		// condition is a constant, do NOT produce code
    SKIP_UNKNOWN	// condition is not a constant, produce code
} skip_T;

/*
 * Chain of jump instructions where the end label needs to be set.
 */
typedef struct endlabel_S endlabel_T;
struct endlabel_S {
    endlabel_T	*el_next;	    // chain end_label locations
    int		el_end_label;	    // instruction idx where to set end
};

/*
 * info specific for the scope of :if / elseif / else
 */
typedef struct {
    int		is_seen_else;
    int		is_seen_skip_not;   // a block was unconditionally executed
    int		is_had_return;	    // every block ends in :return
    int		is_if_label;	    // instruction idx at IF or ELSEIF
    endlabel_T	*is_end_label;	    // instructions to set end label
} ifscope_T;

/*
 * info specific for the scope of :while
 */
typedef struct {
    int		ws_top_label;	    // instruction idx at WHILE
    endlabel_T	*ws_end_label;	    // instructions to set end
} whilescope_T;

/*
 * info specific for the scope of :for
 */
typedef struct {
    int		fs_top_label;	    // instruction idx at FOR
    endlabel_T	*fs_end_label;	    // break instructions
} forscope_T;

/*
 * info specific for the scope of :try
 */
typedef struct {
    int		ts_try_label;	    // instruction idx at TRY
    endlabel_T	*ts_end_label;	    // jump to :finally or :endtry
    int		ts_catch_label;	    // instruction idx of last CATCH
    int		ts_caught_all;	    // "catch" without argument encountered
    int		ts_has_finally;	    // "finally" encountered
    int		ts_no_return;	    // one of the blocks did not end in return
} tryscope_T;

typedef enum {
    NO_SCOPE,
    IF_SCOPE,
    WHILE_SCOPE,
    FOR_SCOPE,
    TRY_SCOPE,
    BLOCK_SCOPE
} scopetype_T;

/*
 * Info for one scope, pointed to by "ctx_scope".
 */
typedef struct scope_S scope_T;
struct scope_S {
    scope_T	*se_outer;	    // scope containing this one
    scopetype_T se_type;
    int		se_local_count;	    // ctx_locals.ga_len before scope
    skip_T	se_skip_save;	    // ctx_skip before the block
    union {
	ifscope_T	se_if;
	whilescope_T	se_while;
	forscope_T	se_for;
	tryscope_T	se_try;
    } se_u;
};

/*
 * Entry for "ctx_locals".  Used for arguments and local variables.
 */
typedef struct {
    char_u	*lv_name;
    type_T	*lv_type;
    int		lv_idx;		// index of the variable on the stack
    int		lv_from_outer;	// nesting level, using ctx_outer scope
    int		lv_const;	// when TRUE cannot be assigned to
    int		lv_arg;		// when TRUE this is an argument
} lvar_T;

// Destination for an assignment or ":unlet" with an index.
typedef enum {
    dest_local,
    dest_option,
    dest_func_option,
    dest_env,
    dest_global,
    dest_buffer,
    dest_window,
    dest_tab,
    dest_vimvar,
    dest_script,
    dest_reg,
    dest_expr,
} assign_dest_T;

// Used by compile_lhs() to store information about the LHS of an assignment
// and one argument of ":unlet" with an index.
typedef struct {
    assign_dest_T   lhs_dest;	    // type of destination

    char_u	    *lhs_name;	    // allocated name excluding the last
				    // "[expr]" or ".name".
    size_t	    lhs_varlen;	    // length of the variable without
				    // "[expr]" or ".name"
    char_u	    *lhs_whole;	    // allocated name including the last
				    // "[expr]" or ".name" for :redir
    size_t	    lhs_varlen_total; // length of the variable including
				      // any "[expr]" or ".name"
    char_u	    *lhs_dest_end;  // end of the destination, including
				    // "[expr]" or ".name".
    char_u	    *lhs_end;	    // end including any type

    int		    lhs_has_index;  // has "[expr]" or ".name"

    int		    lhs_new_local;  // create new local variable
    int		    lhs_opt_flags;  // for when destination is an option
    int		    lhs_vimvaridx;  // for when destination is a v:var

    lvar_T	    lhs_local_lvar; // used for existing local destination
    lvar_T	    lhs_arg_lvar;   // used for argument destination
    lvar_T	    *lhs_lvar;	    // points to destination lvar
    int		    lhs_scriptvar_sid;
    int		    lhs_scriptvar_idx;

    int		    lhs_has_type;   // type was specified
    type_T	    *lhs_type;
    type_T	    *lhs_member_type;

    int		    lhs_append;	    // used by ISN_REDIREND
} lhs_T;

/*
 * Context for compiling lines of a :def function.
 * Stores info about the local variables and condition stack.
 */
struct cctx_S {
    ufunc_T	*ctx_ufunc;	    // current function
    int		ctx_lnum;	    // line number in current function
    char_u	*ctx_line_start;    // start of current line or NULL
    garray_T	ctx_instr;	    // generated instructions

    int		ctx_prev_lnum;	    // line number below previous command, for
				    // debugging

    compiletype_T ctx_compile_type;

    garray_T	ctx_locals;	    // currently visible local variables

    int		ctx_has_closure;    // set to one if a closure was created in
				    // the function

    skip_T	ctx_skip;
    scope_T	*ctx_scope;	    // current scope, NULL at toplevel
    int		ctx_had_return;	    // last seen statement was "return"

    cctx_T	*ctx_outer;	    // outer scope for lambda or nested
				    // function
    int		ctx_outer_used;	    // var in ctx_outer was used

    garray_T	ctx_type_stack;	    // type of each item on the stack
    garray_T	*ctx_type_list;	    // list of pointers to allocated types

    int		ctx_has_cmdmod;	    // ISN_CMDMOD was generated

    lhs_T	ctx_redir_lhs;	    // LHS for ":redir => var", valid when
				    // lhs_name is not NULL
};

// flags for typval2type()
#define TVTT_DO_MEMBER	    1
#define TVTT_MORE_SPECIFIC  2	// get most specific type for member