What is a parse table representing?

Source: R/expr-is.R

Check whether a parse table corresponds to a certain expression.

is_curly_expr(pd)

is_for_expr(pd)

is_conditional_expr(pd)

is_while_expr(pd)

is_function_call(pd)

is_function_declaration(pd)

is_comment(pd)

is_tilde_expr(pd, tilde_pos = c(1L, 2L))

is_asymmetric_tilde_expr(pd)

is_symmetric_tilde_expr(pd)

Arguments

pd

A parse table.

tilde_pos

Integer vector indicating row-indices that should be checked for tilde. See 'Details'.

Details

A tilde is on the top row in the parse table if it is an asymmetric tilde expression (like ~column), in the second row if it is a symmetric tilde expression (like a~b).

Functions

  • is_curly_expr(): Checks whether pd contains an expression wrapped in curly brackets.

  • is_for_expr(): Checks whether pd contains a for loop.

  • is_conditional_expr(): Checks whether pd contains is a conditional expression.

  • is_while_expr(): Checks whether pd contains a while loop.

  • is_function_call(): Checks whether pd is a function call.

  • is_function_declaration(): Checks whether pd is a function declaration.

  • is_comment(): Checks for every token whether or not it is a comment.

  • is_tilde_expr(): Checks whether pd contains a tilde.

  • is_asymmetric_tilde_expr(): If pd contains a tilde, checks whether it is asymmetrical.

  • is_symmetric_tilde_expr(): If pd contains a tilde, checks whether it is symmetrical.

See also

Other third-party style guide helpers: next_non_comment(), scope_normalize()

Examples

code <- "if (TRUE) { 1 }"
pd <- compute_parse_data_nested(code)
is_curly_expr(pd)
#> [1] FALSE
child_of_child <- pd$child[[1]]$child[[5]]
is_curly_expr(child_of_child)
#> [1] TRUE

code <- "for (i in 1:5) print(1:i)"
pd <- compute_parse_data_nested(code)
is_for_expr(pd)
#> [1] FALSE
is_for_expr(pd$child[[1]])
#> [1] TRUE

code <- "if (TRUE) x <- 1 else x <- 0"
pd <- compute_parse_data_nested(code)
is_conditional_expr(pd)
#> [1] FALSE
is_conditional_expr(pd$child[[1]])
#> [1] TRUE

code <- "x <- list(1:3)"
pd <- compute_parse_data_nested(code)
is_function_call(pd)
#> [1] FALSE
child_of_child <- pd$child[[1]]$child[[3]]
is_function_call(child_of_child)
#> [1] TRUE

code <- "foo <- function() NULL"
pd <- compute_parse_data_nested(code)
is_function_declaration(pd)
#> [1] FALSE
child_of_child <- pd$child[[1]]$child[[3]]
is_function_declaration(child_of_child)
#> [1] TRUE

code <- "x <- 1 # TODO: check value"
pd <- compute_parse_data_nested(code)
is_comment(pd)
#> [1] FALSE  TRUE

code <- "lm(wt ~ mpg, mtcars)"
pd <- compute_parse_data_nested(code)
is_tilde_expr(pd$child[[1]]$child[[3]])
#> [1] TRUE
is_symmetric_tilde_expr(pd$child[[1]]$child[[3]])
#> [1] TRUE
is_asymmetric_tilde_expr(pd$child[[1]]$child[[3]])
#> [1] FALSE