diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 38 |
1 files changed, 34 insertions, 4 deletions
@@ -32070,9 +32070,10 @@ Examples of strings which are not absolute paths. $:\eabc .cble -.coNP Function @ read +.coNP Functions @ read and @ iread .synb -.mets (read >> [ source >> [ error-stream >> [ error-return-value <> [ name ]]]]) +.mets (read >> [ source >> [ error-stream >> [ error-retval <> [ name ]]]]) +.mets (iread >> [ source >> [ error-stream >> [ error-retval <> [ name ]]]]) .syne .desc The @@ -32110,15 +32111,44 @@ is a string. If there are no parse errors, the function returns the parsed data structure. If there are parse errors, and the -.meta error-return-value +.meta error-retval parameter is present, its value is returned. If the -.meta error-return-value +.meta error-retval parameter is not present, then an exception of type .code syntax-error is thrown. +The +.code iread +function ("interactive read") is similar to +.code read +except that it parses a modified version of the syntax. The modified +syntax does not support the application of the dot and dotdot operators +on a toplevel expression. For instance, if the input is +.code a.b +or +.code a .. b +then +.code iread +will only read the +.code a +token whereas +.code read +will read the entire expression. + +This modified syntax allows +.code iread +to return immediately when an expression is recognized, which is the +expected behavior if the input is being read from an interactive terminal. +By contrast, +.code read +waits for more input after seeing a complete expression, because of the +possibility that the expression will be further extended by means of the dot or +dotdot operators. An explicit end-of-input signal must be given from the +terminal to terminate the expression. + .SS* Stream Output Indentation \*(TL streams provide support for establishing hanging indentations in text output. Each stream which supports output has a built-in state variable |