builtin,vdoc: fix the examples for the builtin methods, so that v doc -check-examples -time -f ansi vlib/builtin/ pass

cmd/tools/vdoc/run_examples.v

@@ -16,6 +16,7 @@ fn (mut vd VDoc) process_all_examples(contents []doc.DocNode) {
 }
 
 const normalised_default_vmodules_path = os.vmodules_dir().replace('\\', '/')
+const vdoc_max_fails = os.getenv_opt('VDOC_MAX_FAILS') or { '999' }.int()
 
 fn get_mod_name_by_file_path(file_path string) string {
 	mut mcache := vmod.get_cache()
@@ -51,9 +52,11 @@ fn (mut vd VDoc) run_examples(dn doc.DocNode) {
 			os.rm(sfile) or {}
 		}
 	}
-	mut failures := 0
-	mut oks := 0
 	for example in examples {
+		if vd.example_failures >= vdoc_max_fails {
+			eprintln('> vdoc: too many examples failed in ${vd.cfg.run_examples} mode')
+			exit(1)
+		}
 		code := example.all_after('Example:').all_after('example:').trim_space()
 		mod_name := get_mod_name_by_file_path(dn.file_path)
 		vsource_path := os.join_path(efolder, 'example_${rand.ulid()}.v')
@@ -61,6 +64,7 @@ fn (mut vd VDoc) run_examples(dn doc.DocNode) {
 		import_clause := if mod_name in ['builtin', ''] { '' } else { 'import ${mod_name}\n' }
 		source := '${import_clause}fn main() {\n\t${code}\n}\n'
 		os.write_file(vsource_path, source) or { continue }
+		vd.vprintln('>>> vd.example_oks: ${vd.example_oks:5} | vd.example_failures: ${vd.example_failures:5} | examples.len: ${examples.len} | source.len: ${source.len:5} | dn.name: ${dn.name}')
 		cmd := '${os.quoted_path(vexe)} ${voptions} ${os.quoted_path(vsource_path)}'
 		res := os.execute(cmd)
 		if res.exit_code != 0 {
@@ -68,12 +72,10 @@ fn (mut vd VDoc) run_examples(dn doc.DocNode) {
 			eprintln('     cmd: ${cmd}')
 			eprintln('  result:')
 			eprintln(res.output)
-			failures++
+			vd.example_failures++
 			continue
 		}
 		example_program_source_files << vsource_path
-		oks++
+		vd.example_oks++
 	}
-	vd.example_failures += failures
-	vd.example_oks += oks
 }

vlib/builtin/array.v

@@ -369,7 +369,7 @@ pub fn (mut a array) delete(i int) {
 // Example:
 // ```v
 // mut a := [1, 2, 3, 4, 5, 6, 7, 8, 9]
-// b := a[..9] // creates a `slice` of `a`, not a clone
+// b := unsafe { a[..9] } // creates a `slice` of `a`, not a clone
 // a.delete_many(4, 3) // replaces `a` with a modified clone
 // dump(a) // a: [1, 2, 3, 4, 8, 9] // `a` is now different
 // dump(b) // b: [1, 2, 3, 4, 5, 6, 7, 8, 9] // `b` is still the same
@@ -413,7 +413,7 @@ pub fn (mut a array) delete_many(i int, size int) {
 
 // clear clears the array without deallocating the allocated data.
 // It does it by setting the array length to `0`
-// Example: a.clear() // `a.len` is now 0
+// Example: mut a := [1,2]; a.clear(); assert a.len == 0
 pub fn (mut a array) clear() {
 	a.len = 0
 }
@@ -430,7 +430,7 @@ pub fn (mut a array) reset() {
 
 // trim trims the array length to `index` without modifying the allocated data.
 // If `index` is greater than `len` nothing will be changed.
-// Example: a.trim(3) // `a.len` is now <= 3
+// Example: mut a := [1,2,3,4]; a.trim(3); assert a.len == 10
 pub fn (mut a array) trim(index int) {
 	if index < a.len {
 		a.len = index
@@ -520,11 +520,14 @@ pub fn (a array) last() voidptr {
 // Example:
 // ```v
 // mut a := [1, 2, 3, 4, 5, 6, 7, 8, 9]
-// b := a[..9] // creates a "view" into the same memory
-// c := a.pop() // c == 9
+// b := unsafe{ a[..9] } // creates a "view" (also called a slice) into the same memory
+// c := a.pop()
+// assert c == 9
 // a[1] = 5
 // dump(a) // a: [1, 5, 3, 4, 5, 6, 7, 8]
 // dump(b) // b: [1, 5, 3, 4, 5, 6, 7, 8, 9]
+// assert a.len == 8
+// assert b.len == 9
 // ```
 pub fn (mut a array) pop() voidptr {
 	// in a sense, this is the opposite of `a << x`
@@ -816,9 +819,9 @@ pub fn (a &array) free() {
 // Each function takes a boolean test expression as its single argument.
 // These test expressions may use `it` as a pointer to a single element at a time.
 //
-// Example: array.filter(it < 5) // create an array of elements less than 5
-// Example: array.filter(it % 2 == 1) // create an array of only odd elements
-// Example: array.filter(it.name[0] == `A`) // create an array of elements whose `name` field starts with 'A'
+// Example: a := [10,20,30,3,5,99]; assert a.filter(it < 5) == [3,5] // create an array of elements less than 5
+// Example: a := [10,20,30,3,5,99]; assert a.filter(it % 2 == 1) == [3,5,99] // create an array of only odd elements
+// Example: struct Named { name string }; a := [Named{'Abc'}, Named{'Bcd'}, Named{'Az'}]; assert a.filter(it.name[0] == `A`).len == 2
 pub fn (a array) filter(predicate fn (voidptr) bool) array
 
 // any tests whether at least one element in the array passes the test.
@@ -827,15 +830,15 @@ pub fn (a array) filter(predicate fn (voidptr) bool) array
 // It returns `true` if it finds an element passing the test. Otherwise,
 // it returns `false`. It doesn't modify the array.
 //
-// Example: array.any(it % 2 == 1) // will return true if any element is odd
-// Example: array.any(it.name == 'Bob') // will yield `true` if any element has `.name == 'Bob'`
+// Example: a := [2,3,4]; assert a.any(it % 2 == 1) // 3 is odd, so this will pass
+// Example: struct Named { name string }; a := [Named{'Bob'}, Named{'Bilbo'}]; assert a.any(it.name == 'Bob') // the first element will match
 pub fn (a array) any(predicate fn (voidptr) bool) bool
 
 // count counts how many elements in array pass the test.
 // Ignore the function signature. `count` does not take an actual callback. Rather, it
 // takes an `it` expression.
 //
-// Example: array.count(it % 2 == 1) // will return how many elements are odd
+// Example: a := [10,3,5,7]; assert a.count(it % 2 == 1) == 3 // will return how many elements are odd
 pub fn (a array) count(predicate fn (voidptr) bool) int
 
 // all tests whether all elements in the array pass the test.
@@ -844,7 +847,7 @@ pub fn (a array) count(predicate fn (voidptr) bool) int
 // It returns `false` if any element fails the test. Otherwise,
 // it returns `true`. It doesn't modify the array.
 //
-// Example: array.all(it % 2 == 1) // will return true if every element is odd
+// Example: a := [3,5,7,9]; assert a.all(it % 2 == 1) // will return true if every element is odd
 pub fn (a array) all(predicate fn (voidptr) bool) bool
 
 // map creates a new array populated with the results of calling a provided function
@@ -873,9 +876,9 @@ pub fn (a array) map(callback fn (voidptr) voidptr) array
 // The expression uses 2 'magic' variables `a` and `b` as pointers to the two elements
 // being compared.
 //
-// Example: array.sort() // will sort the array in ascending order
-// Example: array.sort(b < a) // will sort the array in descending order
-// Example: array.sort(b.name < a.name) // will sort descending by the .name field
+// Example: mut aa := [5,2,1,10]; aa.sort(); assert aa == [1,2,5,10] // will sort the array in ascending order
+// Example: mut aa := [5,2,1,10]; aa.sort(b < a); assert aa == [10,5,2,1] // will sort the array in descending order
+// Example: struct Named { name string }; mut aa := [Named{'Abc'}, Named{'Xyz'}]; aa.sort(b.name < a.name); assert aa.map(it.name) == ['Abc', 'Xyz'] // will sort descending by the .name field
 pub fn (mut a array) sort(callback fn (voidptr, voidptr) int)
 
 // sorted returns a sorted copy of the original array. The original array is *NOT* modified.
@@ -894,9 +897,8 @@ pub fn (a &array) sorted(callback fn (voidptr, voidptr) int) array
 //
 // Example:
 // ```v
-// fn main() {
-// 	mut a := ['hi', '1', '5', '3']
-// 	a.sort_with_compare(fn (a &string, b &string) int {
+// mut a := ['hi', '1', '5', '3']
+// a.sort_with_compare(fn (a &string, b &string) int {
 // 		if a < b {
 // 			return -1
 // 		}
@@ -904,9 +906,8 @@ pub fn (a &array) sorted(callback fn (voidptr, voidptr) int) array
 // 			return 1
 // 		}
 // 		return 0
-// 	})
-// 	assert a == ['1', '3', '5', 'hi']
-// }
+// })
+// assert a == ['1', '3', '5', 'hi']
 // ```
 pub fn (mut a array) sort_with_compare(callback fn (voidptr, voidptr) int) {
 	$if freestanding {
@@ -934,7 +935,7 @@ pub fn (a &array) sorted_with_compare(callback fn (voidptr, voidptr) int) array
 // It will return `true` if the array contains an element with this value.
 // It is similar to `.any` but does not take an `it` expression.
 //
-// Example: [1, 2, 3].contains(4) == false
+// Example: assert [1, 2, 3].contains(4) == false
 pub fn (a array) contains(value voidptr) bool
 
 // index returns the first index at which a given element can be found in the array or `-1` if the value is not found.
@@ -955,7 +956,7 @@ pub fn (mut a []string) free() {
 // to arrays of different types in different ways.
 
 // str returns a string representation of an array of strings.
-// Example: ['a', 'b', 'c'].str() // => "['a', 'b', 'c']".
+// Example: assert ['a', 'b', 'c'].str() == "['a', 'b', 'c']"
 @[direct_array_access; manualfree]
 pub fn (a []string) str() string {
 	mut sb_len := 4 // 2x" + 1x, + 1xspace

vlib/builtin/chan_option_result.v

@@ -118,7 +118,7 @@ fn trace_error(x string) {
 }
 
 // error returns a default error instance containing the error given in `message`.
-// Example: if ouch { return error('an error occurred') }
+// Example: f := fn (ouch bool) ! { if ouch { return error('an error occurred') } }; f(false)!
 @[inline]
 pub fn error(message string) IError {
 	trace_error(message)
@@ -128,7 +128,7 @@ pub fn error(message string) IError {
 }
 
 // error_with_code returns a default error instance containing the given `message` and error `code`.
-// Example: if ouch { return error_with_code('an error occurred', 1) }
+// Example: f := fn (ouch bool) ! { if ouch { return error_with_code('an error occurred', 1) } }; f(false)!
 @[inline]
 pub fn error_with_code(message string, code int) IError {
 	trace_error('${message} | code: ${code}')

vlib/builtin/int.v

@@ -538,8 +538,8 @@ pub fn (b u8) str_escaped() string {
 }
 
 // is_capital returns `true`, if the byte is a Latin capital letter.
-// Example: assert `H`.is_capital() == true
-// Example: assert `h`.is_capital() == false
+// Example: assert u8(`H`).is_capital() == true
+// Example: assert u8(`h`).is_capital() == false
 @[inline]
 pub fn (c u8) is_capital() bool {
 	return c >= `A` && c <= `Z`

vlib/builtin/map.v

@@ -324,7 +324,7 @@ pub fn (mut m map) move() map {
 
 // clear clears the map without deallocating the allocated data.
 // It does it by setting the map length to `0`
-// Example: a.clear() // `a.len` and `a.key_values.len` is now 0
+// Example: mut m := {'abc': 'xyz', 'def': 'aaa'}; m.clear(); assert m.len == 0
 pub fn (mut m map) clear() {
 	unsafe {
 		if m.key_values.all_deleted != 0 {

vlib/builtin/string.v

@@ -872,7 +872,7 @@ fn (s string) plus_two(a string, b string) string {
 
 // split_any splits the string to an array by any of the `delim` chars.
 // If the delimiter string is empty then `.split()` is used.
-// Example: "first row\nsecond row".split_any(" \n") == ['first', 'row', 'second', 'row']
+// Example: assert "first row\nsecond row".split_any(" \n") == ['first', 'row', 'second', 'row']
 @[direct_array_access]
 pub fn (s string) split_any(delim string) []string {
 	mut res := []string{}
@@ -903,7 +903,7 @@ pub fn (s string) split_any(delim string) []string {
 
 // rsplit_any splits the string to an array by any of the `delim` chars in reverse order.
 // If the delimiter string is empty then `.rsplit()` is used.
-// Example: "first row\nsecond row".rsplit_any(" \n") == ['row', 'second', 'row', 'first']
+// Example: assert "first row\nsecond row".rsplit_any(" \n") == ['row', 'second', 'row', 'first']
 @[direct_array_access]
 pub fn (s string) rsplit_any(delim string) []string {
 	mut res := []string{}
@@ -1837,7 +1837,7 @@ pub fn (s string) trim(cutset string) string {
 }
 
 // trim_indexes gets the new start and end indices of a string when any of the characters given in `cutset` were stripped from the start and end of the string. Should be used as an input to `substr()`. If the string contains only the characters in `cutset`, both values returned are zero.
-// Example: left, right := '-hi-'.trim_indexes('-')
+// Example: left, right := '-hi-'.trim_indexes('-'); assert left == 1; assert right == 3
 @[direct_array_access]
 pub fn (s string) trim_indexes(cutset string) (int, int) {
 	mut pos_left := 0
@@ -2965,7 +2965,7 @@ pub:
 
 // wrap wraps the string `s` when each line exceeds the width specified in `width` .
 // (default value is 80), and will use `end` (default value is '\n') as a line break.
-// Example: `assert 'Hello, my name is Carl and I am a delivery'.wrap(width: 20) == 'Hello, my name is\nCarl and I am a\ndelivery'`
+// Example: assert 'Hello, my name is Carl and I am a delivery'.wrap(width: 20) == 'Hello, my name is\nCarl and I am a\ndelivery'
 pub fn (s string) wrap(config WrapConfig) string {
 	if config.width <= 0 {
 		return ''