From 5277fd9c56619d1fcd4776968b851ea534526435 Mon Sep 17 00:00:00 2001
From: Ben Bridle <ben@derelict.engineering>
Date: Mon, 3 Feb 2025 17:50:10 +1300
Subject: Initial commit

---
 src/lib.rs | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 src/lib.rs

(limited to 'src/lib.rs')

diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..e25725d
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,113 @@
+mod query;
+pub use query::*;
+
+
+pub enum SwitchName {
+    Short(char),
+    Long(String),
+}
+
+
+pub struct Switchboard {
+    // First positional argument.
+    pub program: String,
+    // Positional arguments, stored in reverse order.
+    pub positional: Vec<String>,
+    // Named arguments, stored in forward order.
+    pub switches: Vec<(SwitchName, Option<String>)>,
+    // All arguments following a '--' token, stored in forward order.
+    pub unprocessed: Option<Vec<String>>,
+}
+
+impl Switchboard {
+    pub fn parse(mut args: Vec<String>) -> Self {
+        let mut positional = Vec::new();
+        let mut switches = Vec::new();
+        let mut unprocessed = None;
+        args.reverse();
+
+        while let Some(arg) = args.pop() {
+            if arg.is_empty() {
+                continue;
+            } else if arg == "--" {
+                args.reverse();
+                unprocessed = Some(args);
+                break;
+            } else if let Some(arg) = arg.strip_prefix("--") {
+                let (name, value) = match arg.split_once("=") {
+                    Some((name, "")) => (name, None),
+                    Some((name, value)) => (name, Some(value.to_string())),
+                    None => (arg, None),
+                };
+                if name.is_empty() { continue }
+                switches.push((SwitchName::Long(name.to_string()), value));
+            } else if let Some(arg) = arg.strip_prefix("-") {
+                let (name, value) = match arg.split_once("=") {
+                    Some((name, "")) => (name, None),
+                    Some((name, value)) => (name, Some(value.to_string())),
+                    None => (arg, None),
+                };
+                let chars: Vec<char> = name.chars().collect();
+                if chars.len() != 1 { continue }
+                switches.push((SwitchName::Short(chars[0]), value));
+            } else {
+                positional.push(arg)
+            }
+        }
+        // Reverse order of positional arguments and move program name.
+        positional.reverse();
+        let program = positional.pop().unwrap();
+        Self {
+            program, positional, switches, unprocessed,
+        }
+    }
+
+    pub fn from_env() -> Self {
+        let mut args = Vec::new();
+        for arg_os in std::env::args_os() {
+            args.push(arg_os.to_string_lossy().to_string());
+        }
+        Self::parse(args)
+    }
+
+    pub fn named(&mut self, name: &str) -> NamedSwitchQuery {
+        validate_name(name);
+        NamedSwitchQuery {
+            switchboard: self,
+            name: name.to_string(),
+            short: None,
+            default: None,
+            quick: None,
+        }
+    }
+
+    pub fn positional(&mut self, name: &str) -> PositionalSwitchQuery {
+        validate_name(name);
+        PositionalSwitchQuery {
+            switchboard: self,
+            name: name.to_string(),
+            default: None,
+        }
+    }
+
+    /// Check the next positional argument without consuming it.
+    pub fn peek(&self) -> Option<&str> {
+        self.positional.last().map(|p| p.as_str())
+    }
+
+    /// Consume the next positional argument.
+    pub fn pop(&mut self) {
+        self.positional.pop();
+    }
+}
+
+
+pub enum SwitchboardError {
+}
+
+
+fn validate_name(name: &str) {
+    if !name.chars().all(|c| c.is_ascii_lowercase() || c.is_digit(10) || c == '-') {
+        panic!("Invalid name for argument: {name:?}");
+    }
+}
-- 
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