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Add remove/insert to arrays and maps.

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Stephen Chung
2020-04-10 21:59:29 +08:00
parent 81894e52cb
commit c1b16b1a35
4 changed files with 127 additions and 69 deletions
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README.md
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@@ -1134,18 +1134,18 @@ record == "Bob X. Davis: age 42 ❤\n";
### Built-in functions
The following standard functions (defined in the standard library but excluded if using a [raw `Engine`]) operate on strings:
The following standard methods (defined in the standard library but excluded if using a [raw `Engine`]) operate on strings:
| Function | Description |
| ---------- | ------------------------------------------------------------------------ |
| `len` | returns the number of characters (not number of bytes) in the string |
| `pad` | pads the string with an character until a specified number of characters |
| `append` | Adds a character or a string to the end of another string |
| `clear` | empties the string |
| `truncate` | cuts off the string at exactly a specified number of characters |
| `contains` | checks if a certain character or sub-string occurs in the string |
| `replace` | replaces a substring with another |
| `trim` | trims the string |
| Function | Parameter(s) | Description |
| ---------- | ------------------------------------- | -------------------------------------------------------------------- |
| `len` | _none_ | returns the number of characters (not number of bytes) in the string |
| `pad` | character to pad, target length | pads the string with an character to a specified length |
| `append` | character/string to append | Adds a character or a string to the end of another string |
| `clear` | _none_ | empties the string |
| `truncate` | target length | cuts off the string at exactly a specified number of characters |
| `contains` | character/sub-string to search for | checks if a certain character or sub-string occurs in the string |
| `replace` | target sub-string, replacement string | replaces a substring with another |
| `trim` | _none_ | trims the string of whitespace at the beginning and end |
### Examples
@@ -1193,30 +1193,49 @@ Arrays are disabled via the [`no_index`] feature.
### Built-in functions
The following functions (defined in the standard library but excluded if using a [raw `Engine`]) operate on arrays:
The following methods (defined in the standard library but excluded if using a [raw `Engine`]) operate on arrays:
| Function | Description |
| ------------ | ------------------------------------------------------------------------------------- |
| `push` | inserts an element at the end |
| `append` | concatenates the second array to the end of the first |
| `+` operator | concatenates the first array with the second |
| `pop` | removes the last element and returns it ([`()`] if empty) |
| `shift` | removes the first element and returns it ([`()`] if empty) |
| `len` | returns the number of elements |
| `pad` | pads the array with an element until a specified length |
| `clear` | empties the array |
| `truncate` | cuts off the array at exactly a specified length (discarding all subsequent elements) |
| Function | Parameter(s) | Description |
| ------------ | --------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------- |
| `push` | element to insert | inserts an element at the end |
| `append` | array to append | concatenates the second array to the end of the first |
| `+` operator | first array, second array | concatenates the first array with the second |
| `insert` | element to insert, position<br/>(beginning if <= 0, end if >= length) | insert an element at a certain index |
| `pop` | _none_ | removes the last element and returns it ([`()`] if empty) |
| `shift` | _none_ | removes the first element and returns it ([`()`] if empty) |
| `remove` | index | removes an element at a particular index and returns it, or returns [`()`] if the index is not valid |
| `len` | _none_ | returns the number of elements |
| `pad` | element to pad, target length | pads the array with an element until a specified length |
| `clear` | _none_ | empties the array |
| `truncate` | target length | cuts off the array at exactly a specified length (discarding all subsequent elements) |
### Examples
```rust
let y = [1, 2, 3]; // array literal with 3 elements
y[1] = 42;
let y = [2, 3]; // array literal with 2 elements
print(1 in y); // use 'in' to test if an item exists in the array, prints true
print(9 in y); // ... prints false
y.insert(0, 1); // insert element at the beginning
y.insert(999, 4); // insert element at the end
print(y[1]); // prints 42
y.len() == 4;
y[0] == 1;
y[1] == 2;
y[2] == 3;
y[3] == 4;
(1 in y) == true; // use 'in' to test if an item exists in the array
(42 in y) == false;
y[1] = 42; // array elements can be reassigned
(42 in y) == true;
y.remove(2) == 3; // remove element
y.len() == 3;
y[2] == 4; // elements after the removed element are shifted
ts.list = y; // arrays can be assigned completely (by value copy)
let foo = ts.list[1];
@@ -1238,7 +1257,7 @@ foo == 1;
y.push(4); // 4 elements
y.push(5); // 5 elements
print(y.len()); // prints 5
y.len() == 5;
let first = y.shift(); // remove the first element, 4 elements remaining
first == 1;
@@ -1246,7 +1265,7 @@ first == 1;
let last = y.pop(); // remove the last element, 3 elements remaining
last == 5;
print(y.len()); // prints 3
y.len() == 3;
for item in y { // arrays can be iterated with a 'for' statement
print(item);
@@ -1254,15 +1273,15 @@ for item in y { // arrays can be iterated with a 'for' statement
y.pad(10, "hello"); // pad the array up to 10 elements
print(y.len()); // prints 10
y.len() == 10;
y.truncate(5); // truncate the array to 5 elements
print(y.len()); // prints 5
y.len() == 5;
y.clear(); // empty the array
print(y.len()); // prints 0
y.len() == 0;
```
`push` and `pad` are only defined for standard built-in types. For custom types, type-specific versions must be registered:
@@ -1294,17 +1313,18 @@ Object maps are disabled via the [`no_object`] feature.
### Built-in functions
The following functions (defined in the standard library but excluded if using a [raw `Engine`]) operate on object maps:
The following methods (defined in the standard library but excluded if using a [raw `Engine`]) operate on object maps:
| Function | Description |
| ------------ | ---------------------------------------------------------------------------------------------------------------------------------------- |
| `has` | does the object map contain a property of a particular name? |
| `len` | returns the number of properties |
| `clear` | empties the object map |
| `mixin` | mixes in all the properties of the second object map to the first (values of properties with the same names replace the existing values) |
| `+` operator | merges the first object map with the second |
| `keys` | returns an [array] of all the property names (in random order) |
| `values` | returns an [array] of all the property values (in random order) |
| Function | Parameter(s) | Description |
| ------------ | ----------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
| `has` | property name | does the object map contain a property of a particular name? |
| `len` | _none_ | returns the number of properties |
| `clear` | _none_ | empties the object map |
| `remove` | property name | removes a certain property and returns it ([`()`] if the property does not exist) |
| `mixin` | second object map | mixes in all the properties of the second object map to the first (values of properties with the same names replace the existing values) |
| `+` operator | first object map, second object map | merges the first object map with the second |
| `keys` | _none_ | returns an [array] of all the property names (in random order) |
| `values` | _none_ | returns an [array] of all the property values (in random order) |
### Examples
@@ -1322,12 +1342,12 @@ y.a = 42; // access via dot notation
y.baz!$@ = 42; // <- syntax error: only proper variable names allowed in dot notation
y."baz!$@" = 42; // <- syntax error: strings not allowed in dot notation
print(y.a); // prints 42
y.a == 42;
print(y["baz!$@"]); // prints 123.456 - access via index notation
y["baz!$@"] == 123.456; // access via index notation
print("baz!$@" in y); // use 'in' to test if a property exists in the object map, prints true
print("z" in y); // ... prints false
"baz!$@" in y == true; // use 'in' to test if a property exists in the object map, prints true
("z" in y) == false;
ts.obj = y; // object maps can be assigned completely (by value copy)
let foo = ts.list.a;
@@ -1352,7 +1372,12 @@ y.has("xyz") == false;
y.xyz == (); // a non-existing property returns '()'
y["xyz"] == ();
print(y.len()); // prints 3
y.len() == 3;
y.remove("a") == 1; // remove property
y.len() == 2;
y.has("a") == false;
for name in keys(y) { // get an array of all the property names via the 'keys' function
print(name);
@@ -1364,7 +1389,7 @@ for val in values(y) { // get an array of all the property values via the 'valu
y.clear(); // empty the object map
print(y.len()); // prints 0
y.len() == 0;
```
### Parsing from JSON