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patch 8.1.1834: cannot use a lambda as a method

Problem:    Cannot use a lambda as a method.
Solution:   Implement ->{lambda}(). (closes #4768)
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brammool committed Aug 9, 2019
1 parent 0c779e8 commit 22a0c0c4ecd23b6c43f79ba9b92899ca0b426e29
Showing with 120 additions and 48 deletions.
  1. +5 −1 runtime/doc/eval.txt
  2. +103 −47 src/eval.c
  3. +10 −0 src/testdir/test_method.vim
  4. +2 −0 src/version.c
@@ -1217,7 +1217,8 @@ expr8(expr1, ...) |Funcref| function call
When expr8 is a |Funcref| type variable, invoke the function it refers to.


expr8->name([args]) method call *method*
expr8->name([args]) method call *method* *->*
expr8->{lambda}([args])

For methods that are also available as global functions this is the same as: >
name(expr8 [, args])
@@ -1227,6 +1228,9 @@ This allows for chaining, passing the value that one method returns to the
next method: >
mylist->filter(filterexpr)->map(mapexpr)->sort()->join()
<
Example of using a lambda: >
GetPercentage->{x -> x * 100}()->printf('%d%%')

*E274*
"->name(" must not contain white space. There can be white space before the
"->" and after the "(", thus you can split the lines like this: >
@@ -32,6 +32,7 @@ static char *e_cannot_mod = N_("E995: Cannot modify existing variable");
#ifdef FEAT_FLOAT
static char *e_float_as_string = N_("E806: using Float as a String");
#endif
static char *e_nowhitespace = N_("E274: No white space allowed before parenthesis");

#define NAMESPACE_CHAR (char_u *)"abglstvw"

@@ -3693,7 +3694,6 @@ eval_func(
vim_memset(&funcexe, 0, sizeof(funcexe));
funcexe.firstline = curwin->w_cursor.lnum;
funcexe.lastline = curwin->w_cursor.lnum;
funcexe.doesrange = &len;
funcexe.evaluate = evaluate;
funcexe.partial = partial;
funcexe.basetv = basetv;
@@ -4821,6 +4821,95 @@ eval7(
return ret;
}

/*
* Call the function referred to in "rettv".
*/
static int
call_func_rettv(
char_u **arg,
typval_T *rettv,
int evaluate,
dict_T *selfdict,
typval_T *basetv)
{
partial_T *pt = NULL;
funcexe_T funcexe;
typval_T functv;
char_u *s;
int ret;

// need to copy the funcref so that we can clear rettv
if (evaluate)
{
functv = *rettv;
rettv->v_type = VAR_UNKNOWN;

/* Invoke the function. Recursive! */
if (functv.v_type == VAR_PARTIAL)
{
pt = functv.vval.v_partial;
s = partial_name(pt);
}
else
s = functv.vval.v_string;
}
else
s = (char_u *)"";

vim_memset(&funcexe, 0, sizeof(funcexe));
funcexe.firstline = curwin->w_cursor.lnum;
funcexe.lastline = curwin->w_cursor.lnum;
funcexe.evaluate = evaluate;
funcexe.partial = pt;
funcexe.selfdict = selfdict;
funcexe.basetv = basetv;
ret = get_func_tv(s, -1, rettv, arg, &funcexe);

/* Clear the funcref afterwards, so that deleting it while
* evaluating the arguments is possible (see test55). */
if (evaluate)
clear_tv(&functv);

return ret;
}

/*
* Evaluate "->method()".
* "*arg" points to the '-'.
* Returns FAIL or OK. "*arg" is advanced to after the ')'.
*/
static int
eval_lambda(
char_u **arg,
typval_T *rettv,
int evaluate,
int verbose) /* give error messages */
{
typval_T base = *rettv;
int ret;

// Skip over the ->.
*arg += 2;
rettv->v_type = VAR_UNKNOWN;

ret = get_lambda_tv(arg, rettv, evaluate);
if (ret == NOTDONE)
return FAIL;
else if (**arg != '(')
{
if (verbose)
{
if (*skipwhite(*arg) == '(')
semsg(_(e_nowhitespace));
else
semsg(_(e_missingparen), "lambda");
}
clear_tv(rettv);
return FAIL;
}
return call_func_rettv(arg, rettv, evaluate, NULL, &base);
}

/*
* Evaluate "->method()".
* "*arg" points to the '-'.
@@ -4865,15 +4954,15 @@ eval_method(
else if (VIM_ISWHITE((*arg)[-1]))
{
if (verbose)
semsg(_("E274: No white space allowed before parenthesis"));
semsg(_(e_nowhitespace));
ret = FAIL;
}
else
ret = eval_func(arg, name, len, rettv, evaluate, &base);
}

/* Clear the funcref afterwards, so that deleting it while
* evaluating the arguments is possible (see test55). */
// Clear the funcref afterwards, so that deleting it while
// evaluating the arguments is possible (see test55).
if (evaluate)
clear_tv(&base);

@@ -7455,8 +7544,6 @@ handle_subscript(
{
int ret = OK;
dict_T *selfdict = NULL;
char_u *s;
typval_T functv;

// "." is ".name" lookup when we found a dict or when evaluating and
// scriptversion is at least 2, where string concatenation is "..".
@@ -7473,43 +7560,11 @@ handle_subscript(
{
if (**arg == '(')
{
partial_T *pt = NULL;
funcexe_T funcexe;

/* need to copy the funcref so that we can clear rettv */
if (evaluate)
{
functv = *rettv;
rettv->v_type = VAR_UNKNOWN;

/* Invoke the function. Recursive! */
if (functv.v_type == VAR_PARTIAL)
{
pt = functv.vval.v_partial;
s = partial_name(pt);
}
else
s = functv.vval.v_string;
}
else
s = (char_u *)"";

vim_memset(&funcexe, 0, sizeof(funcexe));
funcexe.firstline = curwin->w_cursor.lnum;
funcexe.lastline = curwin->w_cursor.lnum;
funcexe.evaluate = evaluate;
funcexe.partial = pt;
funcexe.selfdict = selfdict;
ret = get_func_tv(s, -1, rettv, arg, &funcexe);

/* Clear the funcref afterwards, so that deleting it while
* evaluating the arguments is possible (see test55). */
if (evaluate)
clear_tv(&functv);
ret = call_func_rettv(arg, rettv, evaluate, selfdict, NULL);

/* Stop the expression evaluation when immediately aborting on
* error, or when an interrupt occurred or an exception was thrown
* but not caught. */
// Stop the expression evaluation when immediately aborting on
// error, or when an interrupt occurred or an exception was thrown
// but not caught.
if (aborting())
{
if (ret == OK)
@@ -7521,11 +7576,12 @@ handle_subscript(
}
else if (**arg == '-')
{
if (eval_method(arg, rettv, evaluate, verbose) == FAIL)
{
clear_tv(rettv);
ret = FAIL;
}
if ((*arg)[2] == '{')
// expr->{lambda}()
ret = eval_lambda(arg, rettv, evaluate, verbose);
else
// expr->name()
ret = eval_method(arg, rettv, evaluate, verbose);
}
else /* **arg == '[' || **arg == '.' */
{
@@ -122,3 +122,13 @@ func Test_method_syntax()
call assert_fails('eval [1, 2, 3]->sort ()', 'E274:')
call assert_fails('eval [1, 2, 3]-> sort ()', 'E260:')
endfunc

func Test_method_lambda()
eval "text"->{x -> x .. " extended"}()->assert_equal('text extended')
eval "text"->{x, y -> x .. " extended " .. y}('more')->assert_equal('text extended more')

call assert_fails('eval "text"->{x -> x .. " extended"} ()', 'E274:')

" todo: lambda accepts more arguments than it consumes
" call assert_fails('eval "text"->{x -> x .. " extended"}("more")', 'E99:')
endfunc
@@ -769,6 +769,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
/**/
1834,
/**/
1833,
/**/

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