fortran-shlex

Modern Fortran port of Python's shlex shell-like lexer. This package implements the simple shlex lexer, inspired by the Python shlex module, and based on the Golang implementation. The interface comes with two functions, split which parses a command-like string and returns an array of allocatable character strings; and shlex that perform the same, but return a list of type(shlex_token) tokens. Error control is optional, via a boolean success keyword or a token that may return an error string.

Install

Just copy and paste shlex_module.f90 into your project. Alternatively, fortran-shlex can be used as a dependency in your Fortran Package Manager project:

[dependencies]
fortran-shlex = { git="https://github.com/perazz/fortran-shlex.git" }

Usage

The split function returns a list of strings, split according to unix shell rules, which support:

• escaping quotes ("...")
• non-escaping quotes ('...')
• line feed, carriage return etc.

use shlex_module

character(len=:), allocatable :: tokens(:)
type(shlex_token) :: error
logical :: success

! Simple usage
tokens = split('my -W"ery" -Llong //Input \n "string"')

! With logical error flag
tokens = split('whatever ',success=success)

! With complete error flag
tokens = split('whatever ',error)
print *, 'error message=',error%string

And the shlex function has the same API, but returns a list of type(shlex_token)s instead of an allocatable character array.

use shlex_module

type(shlex_token), allocatable :: tokens(:)
type(shlex_token) :: error
logical :: success

! Simple usage
tokens = shlex('my -W"ery" -Llong //Input \n "string"')

! With logical error flag
tokens = shlex('whatever ',success=success)

! With complete error flag
tokens = shlex('whatever ',error)
print *, 'error message=',error%string

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Version 1.1.0 - join_spaced to combine spaced compiler flags

Starting with version 1.1.0, a new high-level interface is available:

tokens = split('gfortran -I /include -L /lib -lm', join_spaced=.true., success=success)

When the second argument (join_spaced) is .true., split will:

• combine spaced flags like -I /path into -I/path
• work for any single-letter flags (e.g., -I, -L, -D) if the next token does not begin with -
• still respect quotes and shell-like rules for escaping

This is useful for parsing compiler and linker flags where -I, -L, etc. may be followed by a separate token due to quoting or formatting.

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🆕 Version 1.2.0 – Preserve enclosing quotes with keep_quotes

Starting with version 1.2.0, you can enable optional preservation of quotes around quoted strings using the keep_quotes flag.

tokens = split('gfortran -I /include -L /lib -lm', join_spaced=.true., keep_quotes=.true., success=success)

Works with:

• Escaping quotes ("double quoted")
• Non-escaping quotes ('single quoted')
• Both split and shlex interfaces

Note

• When provided, join_spaced and keep_quotes are both mandatory arguments.

You can also use keep_quotes with join_spaced=.true. to both:

• Combine flags like -I /include into -I/include
• Preserve quotes around tokens

This is especially helpful for tools that need to pass exact arguments to compilers or scripts without losing context from quoting.

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License

The source code in this repository is Licensed under MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT).

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

See also

• fortran-regex
• Golang shlex
• Python shlex
• Rust shlex