code-red
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Experimental toolkit for writing x-to-JavaScript compilers. It is used in Svelte.
The code-red
package exposes three core functions — b
, x
and print
.
b
and x
take a template literal and return an ESTree program body, or a single node:
import { b, x } from 'code-red';
const expression = x`i + j`;
assert.equal(expression.type, 'AssignmentExpression');
assert.equal(expression.operator, '+');
assert.equal(expression.left.name, 'i');
assert.equal(expression.right.name, 'j');
const body = b`
const i = 1;
const j = 2;
const k = i + j;
`;
assert.equal(body.length, 3);
assert.equal(body[0].type, 'VariableDeclaration');
Expressions in template literals correspond to replacement nodes — so you could express the above like so:
const i = x`i`;
const j = x`j`;
const expression = x`${i} + ${j}`;
const body = b`
const ${i} = 1;
const ${j} = 2;
const k = ${expression};
`;
The print
function takes a node and turns it into a {code, map}
object:
const add = x`
function add(${i}, ${j}) {
return ${expression};
}
`;
print(add).code;
/*
function add(i, j) {
return i + j;
}
*/
i.name = 'foo';
j.name = 'bar';
print(add).code;
/*
function add(foo, bar) {
return foo + bar;
}
*/
@
-prefixed names (replaceable globals)So that you can use globals in your code. In Svelte, we use this to insert utility functions.
// input
import { x } from 'code-red';
x`@foo(bar)`
// output
FOO(bar)
#
-prefixed names (automatically deconflicted names)So that you can insert variables in your code without worrying if they clash with existing variable names.
bar
used in user code and in inserted code gets a $1
suffix:
// input
import { x } from 'code-red';
x`
function foo(#bar) {
return #bar * bar;
}`;
// output
function foo(bar$1) {
return bar$1 * bar;
}
Without conflicts, no $1
suffix:
// input
import { b } from 'code-red';
b`const foo = #bar => #bar * 2`;
// output
const foo = bar => bar * 2;
TODO add an optimiser that e.g. collapses consecutive identical if blocks
TODO add a code-red/compiler
module that replaces template literals with the nodes they evaluate to, so that there's nothing to parse at runtime.
TODO support source mappings for inserted nodes with location information.
FAQs
code-red
The npm package code-red receives a total of 334 weekly downloads. As such, code-red popularity was classified as not popular.
We found that code-red demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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