[Tcsh] One-line command parsing

[Christos Zoulas]

The whole parser and lexical analyzer needs to be redone. Patching it is a losing cause.


christos

> On Aug 24, 2026, at 12:59 PM, Matheus <tateusg at protonmail.com> wrote:
> 
> Because I first tried to implement this on top of a temporary function, I altered how semicolons are parsed. Notably, the command-line must end with a semicolon. This is only true when a semicolon is inserted. I.e.: a ; b ;. However, the behavior in sh.sem.c wasn't altered.
> 
> Though I don't know if this is the best solution to implement one-line command parsing for control structures, this is what I achieved.
> 
> I've only decided to implement this because of this issue somebody posted on my repository. I, for one, couldn't care less whether one-line command parsing for control structures is a feature or not. I mean one could achieve this behavior using a function.
> 
> Regarding functions, I came to realize the implementation is somewhat bad. I dislike the use of pipe(). This is messy. I need to reorganize the project.
> 
>> What is the implication for the existing syntax? I.e. how are existing scripts affected?
>> 
>> christos
>> 
>>> On Aug 24, 2026, at 10:51 AM, Matheus <tateusg at protonmail.com> wrote:
>>> 
>>> https://github.com/Krush206/etcsh/pull/2
>>> Hello. I'm writing this e-mail as a matter of contribution. I forked Tcsh, and added some features. My most-recent contribution is on one-line command parsing. I'm currently working on an implementation to parse control structures in a single line, as in Bourne shells.
>>> 
>>> At first, I thought on parsing one-line commands on top of a temporary function. This turned out to be too complicated. Instead, I parse semicolons into a new node mode [NODE_FUNC]. I implemented a new mode [F_LINE]. I "reparse" the entire tree, setting the F_LINE bit to every command node [NODE_COMMAND]. Then, in execute(), I walk through the entire tree, analyzing which of the NODE_COMMAND entries contain the F_LINE mode. The node shall be saved in a circular linked list for each containing the F_LINE mode. Next, the circular linked list is analyzed from search1(). The parsing is almost the same from search().
>>> 
>>> This is still a work in progress. Not ready for production use. I don't know if this is 100% feasible, though, compared to past implementations, progressed quite fairly.
>>> 
>>> I'd appreciate for contributions and feedback.
>>> 
>>> Thank you.
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>> 
>>