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Computed expressions respect left-to-right associativity and operator precedence #1090

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merged 13 commits into from
Jun 24, 2020
Merged

Computed expressions respect left-to-right associativity and operator precedence #1090

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241259d
WIP: associative operators without parens
sc1f Jun 9, 2020
f203cd7
Associative operators
sc1f Jun 9, 2020
353938a
WIP: actually actually associative operators
sc1f Jun 10, 2020
8be7542
add exponent precedence
sc1f Jun 10, 2020
0c29b3e
reformat parser tests
sc1f Jun 10, 2020
220413c
functions can now have arbitary expressions inside of them without pa…
sc1f Jun 10, 2020
507ddeb
Add invariant tests for expression parser
sc1f Jun 11, 2020
b4a8232
Add more invariant tests
sc1f Jun 11, 2020
0371d4b
WIP: autocomplete fixes for associative expressions, select the right…
sc1f Jun 12, 2020
94a77a4
Reduce usage of get_last_token functions and replace with actual bool…
sc1f Jun 15, 2020
58a2d61
Errors and tokens render side to side in expression editor, thus text…
sc1f Jun 15, 2020
3dfcbef
Only render operators/functions of the correct types
sc1f Jun 15, 2020
d6011b9
reduce the amount of times tokens are cleaned of whitespace
sc1f Jun 16, 2020
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Associative operators
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@sc1f
sc1f committed Jun 23, 2020
commit f203cd76e3b9da986606c5b780d70ae0928f41a6
162 changes: 46 additions & 116 deletions packages/perspective-viewer/src/js/computed_expressions/computed_expression_parser.js
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Original file line number Diff line number Diff line change
Expand Up @@ -73,9 +73,9 @@ class PerspectiveComputedExpressionParser {
this._metadata = metadata;

// Initialize lexer, parser, and visitor
this._construct_lexer();
this._construct_parser();
this._construct_visitor();
this._lexer = this._construct_lexer();
this._parser = this._construct_parser();
this._visitor = this._construct_visitor();

this.is_initialized = true;
}
Expand Down Expand Up @@ -120,8 +120,6 @@ class PerspectiveComputedExpressionParser {
throw new Error(message);
}

console.log(cst);

return this._visitor.visit(cst);
}

Expand Down Expand Up @@ -280,7 +278,7 @@ class PerspectiveComputedExpressionParser {
this._tokens.push(UpperLowerCaseTokenType);
this._vocabulary[UpperLowerCaseTokenType.name] = UpperLowerCaseTokenType;

this._lexer = new Lexer(this._tokens, {
return new Lexer(this._tokens, {
errorMessageProvider: PerspectiveLexerErrorMessage
});
}
Expand Down Expand Up @@ -321,7 +319,7 @@ class PerspectiveComputedExpressionParser {
* Construct a singleton parser instance that will be reused.
*/
_construct_parser() {
this._parser = new ComputedExpressionColumnParser(this._vocabulary);
return new ComputedExpressionColumnParser(this._vocabulary);
}

/**
Expand All @@ -338,9 +336,28 @@ class PerspectiveComputedExpressionParser {
this.validateVisitor();
}

/**
* Given a parsed expression, visit each node and return an array
* of computed column specifications representing the recursive
* tree-walk of all computed columns and their dependencies.
*
* @param {*} ctx
*/
SuperExpression(ctx) {
let computed_columns = [];

this.visit(ctx.Expression, computed_columns);

// An expression may be syntactically valid but does not
// generate new computed columns, i.e. the expression '"Sales"',
// which is syntactically valid but does not have enough
// information to generate a computed column. In the future
// when each column is editable as an expression by default,
// this will not be an issue.
if (computed_columns.length === 0) {
throw new Error("Expression did not generate any computed columns");
}

return computed_columns;
}

Expand All @@ -349,14 +366,14 @@ class PerspectiveComputedExpressionParser {
}

/**
* Visit a single computed column in operator notation and generate
* its specification.
* All operator-type computed columns share the same parsing
* logic.
*
* @param {*} ctx
* @param {Array[Object]} computed_columns an array of computed
* column definitions that are generated from this expression.
*/
OperatorComputedColumn(ctx, computed_columns) {
console.log("operator", ctx);
// TODO: collapse body
_VisitOperatorComputedColumn(ctx, computed_columns) {
let left = this.visit(ctx.left, computed_columns);

let final_column_name;
Expand All @@ -378,8 +395,6 @@ class PerspectiveComputedExpressionParser {
// a + b / c * d + e ... ad infinitum
const left_hand = previous ? previous : left;

console.log(left_hand, operator, right);

// Use custom name if provided through `AS/as/As`
const as = this.visit(ctx.as);
const column_name = as ? as : COMPUTED_FUNCTION_FORMATTERS[operator](left_hand, right);
Expand All @@ -404,102 +419,22 @@ class PerspectiveComputedExpressionParser {
return final_column_name;
}

AdditionOperatorComputedColumn(ctx, computed_columns) {
console.log("addition", ctx);
let left = this.visit(ctx.left, computed_columns);

let final_column_name;

if (ctx.right) {
let previous;

ctx.right.forEach((rhs, idx) => {
let operator = this.visit(ctx.Operator[idx]);

if (!operator) {
return;
}

let right = this.visit(rhs, computed_columns);

// If there is a previous value, use it, otherwise use
// the leftmost value. This enables expressions such as
// a + b / c * d + e ... ad infinitum
const left_hand = previous ? previous : left;

console.log(left_hand, operator, right);

// Use custom name if provided through `AS/as/As`
const as = this.visit(ctx.as);
const column_name = as ? as : COMPUTED_FUNCTION_FORMATTERS[operator](left_hand, right);

computed_columns.push({
column: column_name,
computed_function_name: operator,
inputs: [left_hand, right]
});

previous = column_name;
});

final_column_name = previous;
} else {
// If there are no more right-hand tokens, return the
// column name so it can be used as the tree traversal
// goes upwards.
final_column_name = left;
}
/**
* Visit a single computed column in operator notation and generate
* its specification.
*
* @param {*} ctx
*/
OperatorComputedColumn(ctx, computed_columns) {
return this._VisitOperatorComputedColumn(ctx, computed_columns);
}

return final_column_name;
AdditionOperatorComputedColumn(ctx, computed_columns) {
return this._VisitOperatorComputedColumn(ctx, computed_columns);
}

MultiplicationOperatorComputedColumn(ctx, computed_columns) {
console.log("multiply", ctx);
let left = this.visit(ctx.left, computed_columns);

let final_column_name;

if (ctx.right) {
let previous;

ctx.right.forEach((rhs, idx) => {
let operator = this.visit(ctx.Operator[idx]);

if (!operator) {
return;
}

let right = this.visit(rhs, computed_columns);

// If there is a previous value, use it, otherwise use
// the leftmost value. This enables expressions such as
// a + b / c * d + e ... ad infinitum
const left_hand = previous ? previous : left;

console.log(left_hand, operator, right);

// Use custom name if provided through `AS/as/As`
const as = this.visit(ctx.as);
const column_name = as ? as : COMPUTED_FUNCTION_FORMATTERS[operator](left_hand, right);

computed_columns.push({
column: column_name,
computed_function_name: operator,
inputs: [left_hand, right]
});

previous = column_name;
});

final_column_name = previous;
} else {
// If there are no more right-hand tokens, return the
// column name so it can be used as the tree traversal
// goes upwards.
final_column_name = left;
}

return final_column_name;
return this._VisitOperatorComputedColumn(ctx, computed_columns);
}

/**
Expand All @@ -526,16 +461,9 @@ class PerspectiveComputedExpressionParser {
}
}

// Use custom name if provided through `AS/as/As`me =
const as = this.visit(ctx.as);

let column_name;

// Use custom name if provided through `AS/as/As`
if (as) {
column_name = as;
} else {
column_name = COMPUTED_FUNCTION_FORMATTERS[fn](...input_columns);
}
const column_name = as ? as : COMPUTED_FUNCTION_FORMATTERS[fn](...input_columns);

const computed = {
column: column_name,
Expand All @@ -559,6 +487,8 @@ class PerspectiveComputedExpressionParser {
// string without quotes.
if (ctx.ParentheticalExpression) {
return this.visit(ctx.ParentheticalExpression, computed_columns);
} else if (ctx.FunctionComputedColumn) {
return this.visit(ctx.FunctionComputedColumn, computed_columns);
} else {
return ctx.columnName[0].payload;
}
Expand Down Expand Up @@ -693,7 +623,7 @@ class PerspectiveComputedExpressionParser {
}
}

this._visitor = new ComputedExpressionColumnVisitor();
return new ComputedExpressionColumnVisitor();
}

/**
Expand Down
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