const {
LexRules,
ParseRules,
isIgnored,
onlineParser,
} = require("graphql-language-service-parser");
/**
* The GraphQL mode is defined as a tokenizer along with a list of rules, each
* of which is either a function or an array.
*
* * Function: Provided a token and the stream, returns an expected next step.
* * Array: A list of steps to take in order.
*
* A step is either another rule, or a terminal description of a token. If it
* is a rule, that rule is pushed onto the stack and the parsing continues from
* that point.
*
* If it is a terminal description, the token is checked against it using a
* `match` function. If the match is successful, the token is colored and the
* rule is stepped forward. If the match is unsuccessful, the remainder of the
* rule is skipped and the previous rule is advanced.
*
* This parsing algorithm allows for incremental online parsing within various
* levels of the syntax tree and results in a structured `state` linked-list
* which contains the relevant information to produce valuable typeaheads.
*/
CodeMirror.defineMode("graphql", (config) => {
const parser = onlineParser({
eatWhitespace: (stream) => stream.eatWhile(isIgnored),
lexRules: LexRules,
parseRules: ParseRules,
editorConfig: { tabSize: config.tabSize },
});
return {
config,
startState: parser.startState,
token: parser.token,
indent: function (state, textAfter) {
const levels = state.levels;
// If there is no stack of levels, use the current level.
// Otherwise, use the top level, pre-emptively dedenting for close braces.
const level =
!levels || levels.length === 0
? state.indentLevel
: levels[levels.length - 1] -
(this.electricInput.test(textAfter) ? 1 : 0);
return level * this.config.indentUnit;
},
electricInput: /^\s*[})\]]/,
fold: "brace",
lineComment: "#",
closeBrackets: {
pairs: '()[]{}""',
explode: "()[]{}",
},
};
});