R: Hybrid Index, parsing

hiparse {ff} | R Documentation

## Hybrid Index, parsing

### Description

`hiparse` implements the parsing done in Hybrid Index Preprocessing in order to avoid RAM for expanding index expressions. Not to be called directly

### Usage

    hiparse(x, envir, first = as.integer(NA), last = as.integer(NA))

### Arguments

`x` | an index expression, precisely: `call`
`envir` | the environemtn in which to evaluate components of the index expression
`first` | first index position found so far
`last` | last index position found so far

### Details

This primitive parser recognises the following tokens: numbers like 1, symbols like x, the colon sequence operator `:` and the concat operator `c`. `hiparse` will `Recall` until the index expression is parsed or an unknown token is found. If an unknown token is found, `hiparse` evluates it, inspects it and either accepts it or throws an error, catched by `as.hi.call`, which falls back to evaluating the index expression and dispatching (again) an appropriate `as.hi` method. Reasons for suspending the parsing: if the inspected token is of class 'hi', 'ri', 'bit', 'bitwhich', 'is.logical', 'is.character', 'is.matrix' or has length>16.

### Value

undefined (and redefined as needed by `as.hi.call`)

### Author(s)

Jens Oehlschlägel

### See Also

`hi`, `as.hi.call`

[Package ff version 2.2-13 Index]