Set up initial prototype with basic number parsing

Has one command, is mode-based, no fancy display yet
Added a DESIGN.md for discussion

5 files changed, 757 insertions, 0 deletions

diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..807b127
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,530 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "ahash"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "891477e0c6a8957309ee5c45a6368af3ae14bb510732d2684ffa19af310920f9"
+dependencies = [
+ "getrandom",
+ "once_cell",
+ "version_check",
+]
+
+[[package]]
+name = "arrayvec"
+version = "0.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96d30a06541fbafbc7f82ed10c06164cfbd2c401138f6addd8404629c4b16711"
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "bitvec"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bc2832c24239b0141d5674bb9174f9d68a8b5b3f2753311927c172ca46f7e9c"
+dependencies = [
+ "funty",
+ "radium",
+ "tap",
+ "wyz",
+]
+
+[[package]]
+name = "borsh"
+version = "1.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f58b559fd6448c6e2fd0adb5720cd98a2506594cafa4737ff98c396f3e82f667"
+dependencies = [
+ "borsh-derive",
+ "cfg_aliases",
+]
+
+[[package]]
+name = "borsh-derive"
+version = "1.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7aadb5b6ccbd078890f6d7003694e33816e6b784358f18e15e7e6d9f065a57cd"
+dependencies = [
+ "once_cell",
+ "proc-macro-crate",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.52",
+ "syn_derive",
+]
+
+[[package]]
+name = "bytecheck"
+version = "0.6.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "23cdc57ce23ac53c931e88a43d06d070a6fd142f2617be5855eb75efc9beb1c2"
+dependencies = [
+ "bytecheck_derive",
+ "ptr_meta",
+ "simdutf8",
+]
+
+[[package]]
+name = "bytecheck_derive"
+version = "0.6.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3db406d29fbcd95542e92559bed4d8ad92636d1ca8b3b72ede10b4bcc010e659"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "bytes"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2bd12c1caf447e69cd4528f47f94d203fd2582878ecb9e9465484c4148a8223"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cfg_aliases"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd16c4719339c4530435d38e511904438d07cce7950afa3718a84ac36c10e89e"
+
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
+name = "funty"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6d5a32815ae3f33302d95fdcb2ce17862f8c65363dcfd29360480ba1001fc9c"
+
+[[package]]
+name = "getrandom"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "190092ea657667030ac6a35e305e62fc4dd69fd98ac98631e5d3a2b1575a12b5"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
+[[package]]
+name = "hashbrown"
+version = "0.12.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
+dependencies = [
+ "ahash",
+]
+
+[[package]]
+name = "hashbrown"
+version = "0.14.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "290f1a1d9242c78d09ce40a5e87e7554ee637af1351968159f4952f028f75604"
+
+[[package]]
+name = "indexmap"
+version = "2.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b0b929d511467233429c45a44ac1dcaa21ba0f5ba11e4879e6ed28ddb4f9df4"
+dependencies = [
+ "equivalent",
+ "hashbrown 0.14.3",
+]
+
+[[package]]
+name = "itoa"
+version = "1.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1a46d1a171d865aa5f83f92695765caa047a9b4cbae2cbf37dbd613a793fd4c"
+
+[[package]]
+name = "libc"
+version = "0.2.153"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
+
+[[package]]
+name = "memchr"
+version = "2.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "523dc4f511e55ab87b694dc30d0f820d60906ef06413f93d4d7a1385599cc149"
+
+[[package]]
+name = "num-traits"
+version = "0.2.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da0df0e5185db44f69b44f26786fe401b6c293d1907744beaa7fa62b2e5a517a"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "once_cell"
+version = "1.19.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "proc-macro-crate"
+version = "3.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6d37c51ca738a55da99dc0c4a34860fd675453b8b36209178c2249bb13651284"
+dependencies = [
+ "toml_edit",
+]
+
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.79"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e835ff2298f5721608eb1a980ecaee1aef2c132bf95ecc026a11b7bf3c01c02e"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "ptr_meta"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0738ccf7ea06b608c10564b31debd4f5bc5e197fc8bfe088f68ae5ce81e7a4f1"
+dependencies = [
+ "ptr_meta_derive",
+]
+
+[[package]]
+name = "ptr_meta_derive"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "16b845dbfca988fa33db069c0e230574d15a3088f147a87b64c7589eb662c9ac"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "291ec9ab5efd934aaf503a6466c5d5251535d108ee747472c3977cc5acc868ef"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "radium"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc33ff2d4973d518d823d61aa239014831e521c75da58e3df4840d3f47749d09"
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rend"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71fe3824f5629716b1589be05dacd749f6aa084c87e00e016714a8cdfccc997c"
+dependencies = [
+ "bytecheck",
+]
+
+[[package]]
+name = "rkyv"
+version = "0.7.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5cba464629b3394fc4dbc6f940ff8f5b4ff5c7aef40f29166fd4ad12acbc99c0"
+dependencies = [
+ "bitvec",
+ "bytecheck",
+ "bytes",
+ "hashbrown 0.12.3",
+ "ptr_meta",
+ "rend",
+ "rkyv_derive",
+ "seahash",
+ "tinyvec",
+ "uuid",
+]
+
+[[package]]
+name = "rkyv_derive"
+version = "0.7.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7dddfff8de25e6f62b9d64e6e432bf1c6736c57d20323e15ee10435fbda7c65"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 1.0.109",
+]
+
+[[package]]
+name = "rp_calc"
+version = "0.0.1"
+dependencies = [
+ "rust_decimal",
+ "rust_decimal_macros",
+]
+
+[[package]]
+name = "rust_decimal"
+version = "1.34.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b39449a79f45e8da28c57c341891b69a183044b29518bb8f86dbac9df60bb7df"
+dependencies = [
+ "arrayvec",
+ "borsh",
+ "bytes",
+ "num-traits",
+ "rand",
+ "rkyv",
+ "serde",
+ "serde_json",
+]
+
+[[package]]
+name = "rust_decimal_macros"
+version = "1.34.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e418701588729bef95e7a655f2b483ad64bb97c46e8e79fde83efd92aaab6d82"
+dependencies = [
+ "quote",
+ "rust_decimal",
+]
+
+[[package]]
+name = "ryu"
+version = "1.0.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e86697c916019a8588c99b5fac3cead74ec0b4b819707a682fd4d23fa0ce1ba1"
+
+[[package]]
+name = "seahash"
+version = "4.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1c107b6f4780854c8b126e228ea8869f4d7b71260f962fefb57b996b8959ba6b"
+
+[[package]]
+name = "serde"
+version = "1.0.197"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3fb1c873e1b9b056a4dc4c0c198b24c3ffa059243875552b2bd0933b1aee4ce2"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.197"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7eb0b34b42edc17f6b7cac84a52a1c5f0e1bb2227e997ca9011ea3dd34e8610b"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.52",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.114"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c5f09b1bd632ef549eaa9f60a1f8de742bdbc698e6cee2095fc84dde5f549ae0"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "simdutf8"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f27f6278552951f1f2b8cf9da965d10969b2efdea95a6ec47987ab46edfe263a"
+
+[[package]]
+name = "syn"
+version = "1.0.109"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72b64191b275b66ffe2469e8af2c1cfe3bafa67b529ead792a6d0160888b4237"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.52"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b699d15b36d1f02c3e7c69f8ffef53de37aefae075d8488d4ba1a7788d574a07"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "syn_derive"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1329189c02ff984e9736652b1631330da25eaa6bc639089ed4915d25446cbe7b"
+dependencies = [
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.52",
+]
+
+[[package]]
+name = "tap"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "55937e1799185b12863d447f42597ed69d9928686b8d88a1df17376a097d8369"
+
+[[package]]
+name = "tinyvec"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "87cc5ceb3875bb20c2890005a4e226a4651264a5c75edb2421b52861a0a0cb50"
+dependencies = [
+ "tinyvec_macros",
+]
+
+[[package]]
+name = "tinyvec_macros"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f3ccbac311fea05f86f61904b462b55fb3df8837a366dfc601a0161d0532f20"
+
+[[package]]
+name = "toml_datetime"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3550f4e9685620ac18a50ed434eb3aec30db8ba93b0287467bca5826ea25baf1"
+
+[[package]]
+name = "toml_edit"
+version = "0.21.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a8534fd7f78b5405e860340ad6575217ce99f38d4d5c8f2442cb5ecb50090e1"
+dependencies = [
+ "indexmap",
+ "toml_datetime",
+ "winnow",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
+
+[[package]]
+name = "uuid"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f00cc9702ca12d3c81455259621e676d0f7251cec66a21e98fe2e9a37db93b2a"
+
+[[package]]
+name = "version_check"
+version = "0.9.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "winnow"
+version = "0.5.40"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f593a95398737aeed53e489c785df13f3618e41dbcd6718c6addbf1395aa6876"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "wyz"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05f360fc0b24296329c78fda852a1e9ae82de9cf7b27dae4b7f62f118f77b9ed"
+dependencies = [
+ "tap",
+]
diff --git a/Cargo.toml b/Cargo.toml
new file mode 100644
index 0000000..a337b4c
--- /dev/null
+++ b/Cargo.toml
@@ -0,0 +1,9 @@
+[package]
+name = "rp_calc"
+version = "0.0.1"
+edition = "2021"
+
+[dependencies]
+rust_decimal = { version =  "1.34", features = ["maths", "std", "rand"] }
+rust_decimal_macros = "1.34"
+
diff --git a/DESIGN.md b/DESIGN.md
new file mode 100644
index 0000000..e492633
--- /dev/null
+++ b/DESIGN.md
@@ -0,0 +1,83 @@
+# rp Design Doc
+
+
+## Stages
+
+The plan is to start out rp as a single file prototype, and then, once the basics are in place, start expanding it.
+
+
+### Architechture
+
+The interpter is planned to be a stack-supplied state machine, such that all of the input states are stored on the interpreter struct. This is so that key-by-key commands can be handled directly by the interpreter, at least at first. (If this proves to be -too- complicated to implement, an input editor might be investigated, but I feel confident so far)
+
+Eventually, there will be a TUI display. This I hope to write as a function of an immutable borrow of the stack machine.
+
+
+### Mockups
+
+
+Main screen, shown all of the time
+```
+/---------------------------\
+|  0.#: 123                 |
+|  1.#: 456                 |
+| >2.#: 789_                |
+|  3.$: [This is a string]  |
+|                           |
+| C-h: Help                 |
+| C-r: Registers            |
+| _: Change Sign            |
+\---------------------------/
+```
+
+
+Registers screen, shown in slot two if enabled
+
+```
+/--------------------------\
+| Registers:               |
+| a.@: {1,[abc], 2}        |
+| b.#: 3                   |
+| c.$: [This is a string]  |
+| i.$: [1+]                |
+| g.F: f(x)=[x 1 +]        |
+|                          |
+\--------------------------/
+```
+
+Help screen, shown below any other screens, if enabled
+
+```
+/--------------------------\
+| Help:                    |
+| 1: Arithmetic            |
+| 2: Trig                  |
+| 3: Graphing              |
+| 4: Search                |
+| q: Exit Help             |
+|                          |
+\--------------------------/
+
+```
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..f0aa21a
--- /dev/null
+++ b/README.md
@@ -0,0 +1,4 @@
+# rp: Reverse Polish (calculator)
+
+A stack-based TUI calculator, inspire by dc and the HP-48 calculator.
+
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..bd5053e
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,131 @@
+// use std::env; // TODO: Get args from here
+use std::collections::HashMap;
+use rust_decimal::prelude::*;
+use rust_decimal_macros::dec;
+
+#[derive(Debug)]
+enum Value {
+        Str(String),
+        Num(Decimal),
+}
+
+enum Mode {
+    Integer,
+    Decimal,
+    Str,
+    Command
+}
+
+
+fn main() {
+    let mut state = RPState {
+        registers: HashMap::new(),
+        stack: Vec::new(),
+        mode: Mode::Command,
+        wip_str: String::from(""),
+        num: dec!(0.0),
+        decimal_offset: dec!(1),
+    };
+
+    let result = eval(String::from("123 456 7.89+"), &mut state);
+    match result {
+        Ok(()) => println!("{:?}", state.stack),
+        Err(msg) => println!("Error: {}", msg),
+    }
+}
+
+const RADIX: u32 = 10;
+const INTEGER_RADIX: Decimal = dec!(10);
+
+fn to_decimal(input: u32) -> Decimal {
+    <u32 as Into<Decimal>>::into(input)
+}
+
+
+struct RPState {
+    registers: HashMap<String, Value>,
+    stack: Vec<Value>,
+    mode: Mode,
+    wip_str: String,
+    num: Decimal,
+    decimal_offset: Decimal
+}
+
+fn command(c: char, state: &mut RPState) -> Result<(), String> { 
+    if c.is_digit(RADIX) {
+        state.mode = Mode::Integer;
+        state.num = dec!(0);
+        state.num += to_decimal(c.to_digit(10).ok_or_else(|| format!("{} isn't a digit", c))?);
+        Ok(())
+    } else if c == ' ' {
+        // do nothing
+        Ok(())
+    } else if c == '+' {
+        
+        let a = state.stack.pop().ok_or_else(|| "Data underflow!")?;
+        let b = state.stack.pop().ok_or_else(|| "Data underflow!")?;
+
+        match (a, b) {
+            (Value::Num(c), Value::Num(d)) => { 
+                state.stack.push(Value::Num(c + d));
+            }
+
+            _ => return Err("Invalid operation + on non-numbers!".to_string())
+        }
+        Ok(())
+    } else {
+        panic!("{} isn't implemented yet!", c)
+    }
+}
+
+fn integer(c: char, state: &mut RPState) -> Result<(), String> {
+    if c.is_digit(RADIX) {
+        state.num *= INTEGER_RADIX;
+        state.num += to_decimal(c.to_digit(10).unwrap());
+    } else if c == '.' {
+        state.decimal_offset = dec!(1);
+        state.mode = Mode::Decimal;
+    }
+    else {
+        state.stack.push(Value::Num(state.num));
+        state.mode = Mode::Command;
+        return command(c, state);
+    }
+    return Ok(());
+}
+
+fn decimal(c: char, state: &mut RPState) -> Result<(), String> {
+    if c.is_digit(RADIX) {
+        state.decimal_offset *= dec!(0.1);
+        state.num += to_decimal(c.to_digit(10).unwrap()) * state.decimal_offset;
+    } else {
+        state.stack.push(Value::Num(state.num));
+        state.mode = Mode::Command;
+        return command(c, state);
+    }
+    return Ok(());
+}
+
+fn eval(input: String, state: &mut RPState) -> Result<(), String> {
+    for (_cpos, c) in input.char_indices() {
+        let res = match state.mode {
+            Mode::Command => command(c, state),
+            Mode::Integer => integer(c, state),
+            Mode::Decimal => decimal(c, state),
+            Mode::Str => {
+                panic!("Strings not implemented yet");
+            }
+        };
+        if res.is_err() {
+            return res
+        }
+    }
+    match state.mode {
+        Mode::Integer | Mode::Decimal => { 
+            state.stack.push(Value::Num(state.num));
+            state.mode = Mode::Command;
+        },
+        _ => {}
+    };
+    return Ok(());
+}